Non-working AC thread #3141592
 

Yep, I tried searching....

I have an '87 Carrera with a, as far as I know, stock AC system. The PO converted to R134 (drier change unknown).

A month ago, I got the system recharged and had them add dye. The AC vent would put out ~58F air at ~80F ambient (Houston). A couple weeks later, I noticed it no longer put out cool air and as of today the vent temp is essentially ambient.

What I have checked:
1) I took it back to the shop and they said pressure was good and found no leaks with the UV light.
2) Compressor clutch is engaging, front condenser fan is running, evaporator fan runs in all three speeds and temp knob is at max.
3) I do not see bubbles in the drier sight glass (but also cannot tell if there is flow). See photo two.
4) The inlet side of the rear deck condenser is very hot and the outlet is slightly above ambient.
5) Visual inspection of the TXV revealed nothing but I did notice that the connection to the silver relay/ switch on the passenger side of the smugglers box was loose (top of photo one). I made sure it was fully inserted but it had no apparent effect.

I suspect a bad TXV or plugged component but is there any other potential culprits or checks I can do (without a gauge set)?

Recommendations? Thanks in advance.
http://forums.pelicanparts.com/uploa...1400716225.jpg
http://forums.pelicanparts.com/uploa...1400716243.jpg

Sounds like the dye may have caused a blockage. If the condenser is really hot and the line is at ambient temp then that is where the blockage could be. Seems you have a no flow problem

I would ask if they checked both high side and low side pressure, and what were the readings..

And pic #2 looks like there is no flow.

What is the solution for no flow blockage? Can it be flushed in place or do I need to pull the system apart? I will go back by the shop on Friday and talk to them about pressures and flushing, if possible.

Pfffft. Come on. Dye caused a blockage? If there is blockage, a look inside the sight glass indicates that operation caused a blockage and the expansion valve would be the place I would start.

How about a leak? Is that possible?

Your option would be to take the P-car to a A/C shop and have them put gauges on the system with the compressor running to see if it is pumping refrigerant. Then you will know for sure if it's blocked. One other option would be - it's completely out of refrigerant.

Pic #2 reminds me of documentaries about the Titanic.

That said.

Here is my suggestion. It worked for a little bit, right? That means the system is kind of functioning. Is there a lot of refrigerant in your system? Press on the schrader valves to check. If so, blockage. If not, leak.

Get a new dryer and an expansion valve. Regardless of leak, your system needs revitalizing.

Use and air compressor, mineral spirits and a friend and clean the living snot out of your system.

Dump the oil out of the compressor and replace with PAG. Search on how many ounces or call Griffith's Tech and Charlie will tell you. Put two ounces in the other components - mainly the evaporator and the dryer.

Suck down a vacuum, even with the el-cheap-o Harbor freight $15 unit.

The $50 gauges from the freight would help here.

Recharge with maybe 5 oz less than what the R12 would be and check pressure.

Add a wee bit of R-134 if high side is low based on graphs. Low side will be around 45-50.

Is this optimal. Nah. Compared to what you have it kicks ass.

Alternatively, spend $750 for a refresh of your system by a shop.

This might not have anything to do with your problem, but it looks like the dryer is crushed at the top (near the fitting) - is that the case?

Also you mentioned in your first post that the a/c shop said the pressures were good, if that is correct (if the techs know WTF they are doing), I don't see how you could have any kind of obstruction in the system . . .

Good eye.

That is wrong. The more I look at it the more it looks like the whole tube took a big honkin' whack.

Bottom is whopper-jawed as well. Not dented, just crooked.

I don't think it's your TXV. The TXV meters flow of refrigerant into the evaporator coil. If there was a problem, it would show up in the pressure readings. If the TXV sensing bulb was bad, the valve would "search" meaning it would open and close changing pressures and you'd never get a good pressure reading. An old rule of thumb is that you should have condensation on the suction line.

1. Pressures will vary based on ambient temp. Unless they used a PT chart, they are guessing pressures are good (btw, 1oz of refrigerant won't make that big a difference in pressure but it will make a big difference in operating temperatures. You could just be slightly off on charge.
2. If your clutch is engaging, the compressor should be pumping and there should be sufficient (not full or properly charged just sufficient) refrigerant because most systems use a pressure switch to determine there is refrigerant and that the clutch should engage.
3. You should be able to put a screwdriver to the line and the end to your ear and hear a pulsation from the flow
4. Inlet of the condenser should be hot outlet cooler. The condenser is removing the heat extracted by the refrigerant then cooling and going back for more.
5. RE txv, see my other comment.

I don't do car AC but did AC for a living. Principles don't change just pressures and temperatures.

That drier looks original, and that isn't good. Plus it looks damaged.

As Bob mentioned, the first thing I would do is check for pressure at the Schrader valve. By the looks of it the R134 "conversion" consisted of putting new fittings on the compressor and recharging with R134.

If there is no pressure in the system (check first!) remove one of the A/C lines and see if the O-rings are the original black ones, or if they have been replaced by the green nitrile O-rings. If they are black, they may be a major source of your leakage.

If your compressor works, you have a decent chance of getting a functional system by replacing all of the O-rings, swapping the receiver-drier, and the expansion valve. All those parts can be had for about $70.

Pickup a Harbor Freight vacuum pump & gauge set (about $150 for both -- or borrow them), and you are in business for around $250 (including refrigerant and oil).

Clean the major components as Bob described, swap the O-rings, install new expansion valve, install new receiver drier (do this last), then pull a vacuum and see if it holds. If so, charge it up and Bob's your uncle.

Not the perfect fix (probably marginal for Texas or Arizona) and it will probably leak some over the course of the year. But I get vent temps in the low 40s doing this, and it is good enough (especially on a Cab!)

Good luck.

1) The system was not properly converted to R134a. Besides the sexy shaped drier, you have junk in the sight glass.

2) Unless you want to revisit the AC system monthly, or weekly, you will need as a minimum:
A) Liquid flush hoses, evaporator (with TEV off), condensers, tear down the compressor and inspect it and reseal or replace. You will have to drop the lines that rise above the gravity line; might want to think about just replacing them all a good barrier set while you are at it cause you will be recharging sooner or later because of the stock lines.
B) You can either borrow or buy an AC flush canister and a gallon of AC flush (avoid other chemicals) or buy 4 cans of Interdyanmics CA-1 AC flush
http://forums.pelicanparts.com/uploa...1400758693.jpg
C) You will need a low-high pressure switch.
D) You will need to have a professional evac, charge and test, unless you want to spend your evenings reading the threads here or your weekends "learning" the hard way.

3) When all is said and done, you are not going to be happy with a stock system in your climate. So stop and think where you are headed. And,

Read The Mr. Ice Project

Thus begins the slide down the slippery slope of A/C threads.

Cue wwest to discuss trinary pressure switches and condenser fans or whatever.

Not that kuehl is wrong by any means. But once you go the way of barrier hoses, you are in full-fledged "while you are in there" mode.

As with everything DIY, you have to make your own calculations about money-labor-time-value.

It absolutely can be done in a long Saturday, with a minimal investment (under $300) -- and you can get good results. But they are not guaranteed, and may require seasonal maintenance. You are gambling a small amount of money and some time that there are no major component with serious leaks or damage.

If you want a guaranteed excellent result as kuehl describes, expect to pay 8-10 times that amount.

There is some middle ground between the two approaches (ie, replacing a weak compressor or leaking evaporator), but once you start changing major components & hoses, you may as well go the full monty.

Yup. You will toss away $300 and an easy 15+ hours going down that road.

That is not necessarily true.

I am happy with my $300 results -- and have working A/C. Yes, that is a sample of one.

But I doubt I experienced an A/C miracle.

That is some nasty looking schmeg in that filter drier.
Pull the gas, change the drier, leak check and pull a good vacuum.
a good system flush will probably be in order while your in there.
That would be bare minimum....
If you are looking to end refrigerant emissions (as you should) replace the hoses.

You also need to really LOOK at the evaporator. It is obvious your car is actually driven in the rain as is my car. I bought my car long ago but it was used as a daily driver by the previous owner.

When I did my AC conversion to the dual Kuehl system I planned to replace my evaporator anyway. This is the bottom of my old evaporator.

http://forums.pelicanparts.com/uploa...1400764093.jpg

No doubt that was part of my problem. The AC worked before but was just cool, not cold.

Now it works great.

I added the two rear fender condensers, changed the hoses, receiver-dryer & evaporator. It was expensive but my wife will ride with me in HOT climates and I can keep myself cool.

Driving down the present Road

Typical DIY, first-timer, average flush times:
Time required to remove and reinstall (R&R all hoses: 6-8
Time required to R&R evaporator: 3-5
Time required to R&R 2 stock condensers: 3

Other
Compressor R&R for - Inspection & Reseal: 3
Drier R&R - ½
Source & Procure ‘cheap’ vacuum pump, gauge set - 1
Source & Procure R134a cans - ½
Source & Procure Electronic Sniffer - ½
Source & Procure Drier, O-rings, R134a oil - ½
Figure out how to Evac, Charge and Test - 1 to 3
Proper Evac, Charge and Test - 4 to 5
Leak Check (electronic) - ½
Read Forums and Trouble Shoot - 6+++++
========================================
30-40 Hours

End Result
The vehicle will perform no better than the day it rolled off the factory floor, and in a Houston climate you will not be happy.
And, the more you use a stock type system at those higher Houston ambient temps the quicker the refrigerant will leak out.... hence you will be spending your time back here.

I was traveling down the same A/C road of what do I do. Sometime back I converted my R12 system to R134a on my '87 by doing what COLB suggested with somewhat OK results. However, the longest period of charge I could keep in my system with the old hoses was about 3 months. I had no leaks anywhere determined by leak test except through the old hoses. So, after about the 4th recharge I elected to redo my system by replacing the TEV, new OEM compressor, new drier and last but not least, new hoses. In addition, I pulled the evap for a thorough flush along with flushing both front and rear condenser. For flushing, I used the product that kuehl mentioned in his post above. It works fantastic. After pulling my old hoses I inspected each of them and they were really sad as they had surface cracks all over, and what I assumed was weather checking on just about every hose. Would one expect less after 27 years living under a car? Pulling the hoses is not that big of a job but, just dirty and tedious. Since I live in an area that has a short and mild summer I elected not to install extra fans, new evap etc. as I don't need the A/C that often. Send a PM to kuehl, he definitely knows A/C and he will put you on the right path to having the best working A/C system.

Looks suspiciously as if PO did a DIY conversion to R-134a without the proper procedure of removing the R-12 and oil. My understanding is that mixing the two results in forming an emulsion.

Pay $200 to a professional shop to work from scratch for a conversion. And yes, replace the drier..

Oh, and yes, add a Red Dot trinary pressure switch, your Porsche does not have the high pressure relief valve as below.

It appears that Porsche might have expected the non-barrier hoses to work in the same manner. Certainly appears as if they were correct

From somewhere on the internet:

Suction Side Pressure Relief Valve

Some 1994 and later model Fords may exhibit a repeated, low charge condition with
no leaks found. A suction-side pressure-relief valve, which opens prior to the pre-set
pressure, may cause this condition.

The suction-side pressure-relief valve is designed to open at @ 250 PSI. This is to
prevent damage to the evaporator from excessive, static refrigerant pressure that
develops when the vehicle “heat soaks”. A “heat soak” condition occurs when the
engine is at normal operating temperature, the ignition is turned off, and under-hood
temperature increases. This could cause the static refrigerant pressure to exceed the
burst pressure limit of the evaporator. With a static refrigerant temperature of 150º F,
the static pressure for R134a is 264 PSI. Most evaporators will experience damage
when static pressure exceeds 250 PSI. At such pressure, the valve opens and
dumps refrigerant to the atmosphere.

The pressure spring inside the valve is subject to rapid temperature changes as the
air conditioning system is cycled on and off. The constant changes in temperature
(from warm to cold to warm) can weaken the spring, allowing it to open below 250
PSI.

Suction Side Relief Valve
Discharge Side Relief Valve
.


4S349

One request to Pato911, please after you do whatever you happen to do, let us all know how it worked.

If we can get all the AC threads to be finished with what the owner did and the results achieved it would help eliminate the debate. Good bad or indifferent, please report back with results of your project and what you did.

Have you tried Bob Tindal's suggestion for additional engine cooling in stop and go, slowing moving traffic? It appears that technique might also be an aid in enhancing the A/C operation in those same traffic conditions.

If you try it and it works you might wish to take it a bit further and wire up a simple 12 volt relay, energized by the compressor clutch power and use a N.O. contact set to ground the engine oil temperature sensor signal going to the cabin heat controller.

Without question, the effectiveness of a "minimum" conversion will depend on the condition of your existing system.

If everything looks corroded, bent, and as damaged as your drier, the likelihood of achieving good results goes down.

As to kuehl's estimate of removing hoses to clean them -- that would be insanity. If you are going to pull out your A/Cs hoses, it would be foolish not to replace them with new hoses.

To wwest's point, there are oils that are compatible with R134 and the residual R12 lubricants in your system.

If you want to spend $3k on the A/C, you can get great results. No doubt.

Is that necessary to get a working A/C? Maybe not, depending on the condition of what you have, and your expectations.

Not to turn this A/C discussion into a pi**ing contest but, yes I had the R12 vacuumed out, followed by flush of system less the TEV and compressor. Removed what I could of the old oil from compressor and replaced with 6oz of ester oil. I am not concerned now what/where/when it leaked as that is behind me. What I was trying to share is my experience, what I am doing to make my A/C better to meet my needs and put it behind me. End of story.

I was addressing what the PO might have done, are you the PO?

My apologies, I incorrectly misread the beginning of your post.

Okay....:)

If your evaporator coil and condenser are dirty/plugged, you will see a difference in the pressures and the suction line temps. If you can get to both sides of your evaporator, check the temperature drop across the coil. That will tell you if you're cooling properly. And again, check to see if you have condensation on your suction line. If you don't, believe it or not, you can have either a overcharge or undercharge situation. If you add gas and your suction side temp doesn't drop, you're possibly looking at a overcharged system. AC systems work on both pressure and temperature. To achieve proper cooling, you have to have not only the proper suction pressure but also the proper suction temperature. Blocked coils can change pressures and temperatures so that you don't have proper temperature drop across the coil. This could be a matter that you have to change your metering device (txv) because the txv you have is for R12 not 134.

First, thanks everyone for the quick and useful responses. Like the Marines, you guys get more done before 9am than others do all day.

A couple quick clarifications/ updates:
1) The picture of the drier is very misleading. It is filthy! My car will never be a garage queen and has sadly not been washed in a couple weeks. The drier is straight with no bends, dents, etc. That said, it does look OE and I will plan to replace it.
2) As recommended, I checked the valves on the compressor and both seem to indicate the system still has pressure. At least some green fluid sprayed out on my car key.
3) Kuehl, with regard to your list of activities and time, thanks, but would I not spend equal durations changing everything out to a Kuehl equipment set and, as you advertise, result in a system better than OE?

It sounds like I have a project for the long weekend. I do not have any of the parts on hand (TXV, Drier, etc) but I can check pressure, evac, inspect, and flush the system. I will probably also remove hoses. The car is 27yrs old; I have no issues replacing rubber and other wear components as well as upgrading where technology has improved.

I can get new hoses made locally for ~$65/piece. Unless the committee has a better recommendation, I may just get a drier/ TXV ordered and plan to R&R hoses with reinstall planned for next week.

Are any of you in Houston and will to trade AC expertise/ tool use for food & beer?

a leak pressure test will say there are no leaks while the hoses are hooked up check and replace the actual valves see if there is any oil residue under the caps

Well Pato.... unless you got some camera lens distortion or some funky picture editing going on, I'd say:

1) That's quite a crush you got in the drier at the top, and
2) That's pretty dirty refrigerant oil in the site glass


http://forums.pelicanparts.com/uploa...1400793432.jpg

I'd say rub not crush. There's little if any distortion to the metal. -J

http://forums.pelicanparts.com/uploa...1400796085.jpg

Not buying it. That thing is tore up unless flat does not count as distortion.

Moot as OP is replacing, I hope.

The difference is, do you want to be genuinely cool in Houston or do you want to cut the heat a little with a well functioning stock system?

OK - "some green fluid" is different than I pushed the needle thing in and my friggin' fingers froze because I was doused with a non-stop spray of refrigerant.

Really, really make sure you still have a good shot of refrigerant in there. Otherwise, on your refresh procedure, you really need to locate the leak. It should be evident.

Get the car safely up in the air and prepare to get dirty.

I say, do the $300-500 refresh and get some practice. If you want to put one of Charlie's systems in, you will have some flight time under your belt.

One last point before I get my drink on. You can buy 30lb tanks of r-134 at the car parts store for circa $100. Do the math. That is like eight thousand 12oz cans of R134 that sell for $15+ each.

This thread is a riot.

Crushed cans, flat tires, and the best....... 30 lbs x 16 oz = 480/12 = 40 ? noooo., = 8,000.
Yup, buy a 30 pounder and you can recharge every Pelican car (lacking barrier hoses) here for the next zillion years.

Have you considered, perhaps, a rounding error?

Yes Bob. We reviewed all the data. There were a few chad's. To be fair we including the chads and split the vote 50/50. And, just to be precise as possible we upped the 2nd decimal point 1 full value on the AFR for methanol because lambda always lies.

So, reading between the lines, you are saying that I am off a little in my can equivalence calculation?

I am ok with that. At least I was in the ballpark.