confusing AC gauge readings

[Pazuzu]

My thought are...as long as you're not going over 325, 350ish on the high side, then keep adding a can. You can always REMOVE refrigerant on the side of the road after driving a bit, but it's hard to ADD any.
Put in 35-40 ounces, then remove as needed over the next few weeks.

[Pazuzu]

That's assuming a good clean vacuum, clean lines, clean fill method, etc. If you have a system filled with nothing but oil, R134 and LOVE, then it will produce cooler air out of the dash that what is coming in. Work the details from there. Don't sweat the petty stuff, but do pet the sweaty stuff (until you get cool air out of the dash, then pet the chilly stuff). Any air that is cooler than ambient is better than no air cooler than ambient, which is where we all start when we enter the A/C arena.

All i know is, it's been 102 and 99% humidity here and I'm TIRED OF IT AND WANT COOLING! I have $300 of hoses and fitting and such arriving tomorrow, and I will wait until, oh, November to finally work on it because 102 outside is the same as 254 in my garage.

[88911coupe]

I'll have to do a better job on the sound...it just sounds "noisier" than I recall. I also recall a sharp, very rapid "clackity" sound as the rpm's dropped. I have a stethoscope so may hook that up to see if I can get a more useful description on the sound.
Oh, and we have a cold front coming through...only 98 Wednesday. I'm going to need a sweater.

[Ronnie's.930]

Originally Posted by Bob Kontak

+1 LOL (Akron is such a thermo pussy's paradise)

Ronnie post the dash temp laser pic you sent me

Here's what Bob is talking about - the dash of my truck parked in the sun this afternoon. I always put a sun shield in there, but for this pic, had the corner of it pulled aside for about 5 mins prior to the pic.

Getcha suuuummm of this, you Midwestern and Northern bisches!

[tirwin]

It hasn't been quite as hot here. Only the high 90's with 90% humidity. But it's still hot enough to suck the energy right out of you.

I'm going to have to invest in A/C for the garage one day.

[Ronnie's.930]

Originally Posted by Bob Kontak

I used to wear a jock strap and nothing else to tolerate that kind of heat.

Fixed for accuracy - you're welcome!

[Ronnie's.930]

^^^

More likely that is a pic of the contents of yer toilet following that McDonald's run the other night- three Big Mac meals, a side order of McNuggets (Super Super Sized, buttofcourse) and a XXXXXXXL shake, to go!

[ganun]

Originally Posted by tirwin

.........................
I'm going to have to invest in A/C for the garage one day.

The BEST thing said here BY FAR.

[wwest]

Originally Posted by tirwin

It hasn't been quite as hot here. Only the high 90's with 90% humidity. But it's still hot enough to suck the energy right out of you.

I'm going to have to invest in A/C for the garage one day.

No more OT than a pair of BB's...

FRYS.com*|*SOLEUS

[SilberUrS6]

Bob, Ronnie - focus. Look, you were doing a good job with the help and the suggestions to start a new thread, then you both went off the rails. I suggest, in the most suggestiony way I can, that you delete your OT posts and just post the following: help for the OP, requests for new thread from our resident troll, and encouragement for the DIY n00bz that lurk among us. In post 10, you can see that I'm trying to find out how air got in the system, since that was obviously the problem. Flushing a gas system is a lot like flushing a liquid system. Letting it drain doesn't get out all the stuff you're trying to get out. Likewise, pulling a vacuum doesn't always get out the stuff you want out. You have to flush it out. With another gas. If you pull a vacuum long enough, you might get the stuff out that you want out - physics dictates that. But that's a long time to pull a hard vacuum, and nobody wants that.

So, guys, move back to the original plan. Help where you can, derail the troll where you can. Avoid OT crap that kills the thread and gets it closed.

Edit: Bob, many thanks.

[tirwin]

For a reference point.

My setup:
- new rear decklid condenser (aftermarket, tube and fin)
- Kuehl evaporator
- Kuehl front condenser
- Kuehl front & rear wheel-well condensers

Last Saturday I charged initially to 36 oz of R134a from a 30 lb tank and then topped off using the pressure/temp chart. I ended up with a total of 45 oz discharged from the tank to get to ideal pressure/temp. I'm not sure how to estimate how much refrigerant was left in the hose from the tank to the manifold gauge and from the gauge to the compressor. Say 1-2 oz?

That puts my final charge weight at 43-44 oz (EDIT: fixed typo) or ~7-8 oz over the initial 36 oz fill. I think that sounds about right given the extra condensers.

So the OP seems to be in the right ballpark.

I'd make sure you have an accurate thermometer in your garage and not just rely on the weather report for ambient temp. Grant brought over a really accurate thermometer that we used during the fill procedure. When I compared his to mine, mine was several degrees off which can make a difference if you're using the P/T method.

[wwest]

Originally Posted by tirwin

For a reference point.

My setup:
- new rear decklid condenser (aftermarket, tube and fin)
- Kuehl evaporator
- Kuehl front condenser
- Kuehl front & rear wheel-well condensers

Last Saturday I charged initially to 36 oz of R134a from a 30 lb tanks and then topped off using the pressure/temp chart. I ended up with a total of 45 oz discharged from the tank to get to ideal pressure/temp. I'm not sure how to estimate how much refrigerant was left in the hose from the tank to the manifold gauge and from the gauge to the compressor. Say 1-2 oz?

That puts my final charge weight at 43-45 oz or ~7-8 oz over the initial 36 oz fill. I think that sounds about right given the extra condensers.

So the OP seems to be in the right ballpark.

I'd make sure you have an accurate thermometer in your garage and not just rely on the weather report for ambient temp. Grant brought over a really accurate thermometer that we used during the fill procedure. When I compared his to mine, mine was several degrees off which can make a difference if you're using the P/T method.

Wow, FULL refrigerant charge!

36 Oz "standard", 4 ozs extra for each additional condenser. Since condenser content is gaseous you may be bit overcharged for "standard".

Really interested in knowing vent temperatures and system pressures at/during initial cooldown, interior at/near OAT. Idle and 2000 RPM?

[88911coupe]

OK...update sort of. In light of my odd compressor noise I have decided to replace it. I have determined that it appears I actually have a 508 in my car, not the more common 507. It fits fine and I have found several for sale at a great price but the general consensus seems to be use the 507. Is there any valid, technical reason the 507 is better...or it just more common?

[88911coupe]

Update...just took apart what appears to have been a perfectly fine Sanden compressor, albeit it pretty old. The only "wear" I could find what some faint scratching on the piston skirts. The bores were slick as glass, as was every other wear face I could find. Really no idea what was causing the noise. Still not sure if I should order another SD 508 or a 507.

[Pazuzu]

Originally Posted by 88911coupe

Update...just took apart what appears to have been a perfectly fine Sanden compressor, albeit it pretty old. The only "wear" I could find what some faint scratching on the piston skirts. The bores were slick as glass, as was every other wear face I could find. Really no idea what was causing the noise. Still not sure if I should order another SD 508 or a 507.

SD508 is slightly longer than a 507. If you currently have a 508 and it fits, then go with it again. The 507 works better with Carrera intakes, carbs and fuel injection setups. I have a 508 in mine, which barely clears the SC intake runner.

[88911coupe]

From what I can determine from the Sanden tech guide is that the SD5H11/SD507 are effectively the same with the 511 being the "R134" version. Same for the SD5H14/SD508 with the 508/514 having a 8.4 in displacement vs the 507/511 having 6.6 cubic inches. I have seen comments on other threads implying having too much capacity is not good...i.e. "bigger is not better". I've seen this issue come up in home ac systems as well.
I can find both versions of them easily but just trying to clarify which one is "better" from an application specific point.

[88911coupe]

Ok update and request for help/opinions...
I replaced the vac pump b/c I'd accidentally let the oil get really low in my old HF pump so now have nice Mastercool. I thought maybe the old pump not pulling good vac.
ThursdyHooked up new pump and pulled vac several times over 24 hours 2-3 hours at time. I'd turn it off and close gauges. No leaks.
Forgot to mention before new vac pump did one more try at recharge. I SLOWLY added 4 cans of r134 and vent temps NEVER got below upper 50s so got new vac pump. Ok back to current issue.
Friday added 2 12 oz cans r134 and again vent temps never got below 60 or so....grrrrr!
Got annoyed and decided to shut it down and have a couple of beers. BTW pressures were 30 tad over 300.
Yesterday decided to run it again and see how it did. Note that I have a temp sensor from a digital VM inserted into the evap core the themostat probe.
Here is odd part
Lid down and sealed, ambient 81 fired up car, turned on AC full then watched sensor in core.
Immediately dropped to low 40's so thinking maybe system ok but in few minutes crept up to upper 40's. Pressure at idle 35/250
After about 8-10 minutes core in low 50s
Had wife hold rpm at 2000 pressure 17/250 (why didn't high side increase?)
Also at higher rom core temp WENT UP to 58...WTH!?
Dropped back to idle core temp crept down to 52!
Does this indicate anything? I was thinks make undercharged but can't understand why core temp so low? Really getting frustrated with this.

[kuehl]

Assuming......
1) You have only 24 oz in the system.
2) At 81F ambient.
3) You are checking the gauges with the engine deck lid down resting on the hoses
4) The evaporator outlet pipe is cold to sweating and not frosted.
5) Front condenser blower motor is running when clutch engages.
6) Your VM probe; you tested it before inserting in evap core, and its in the evap core rather than through it all the way (must be making good contact with evap cooling fins).

"Possible" air in the system related to evacuation procedure or introduction of air when swapping refrigerant cans (refrigerant line must be purge, no air). Assuming the system, for example used 47 oz R12, you should be around 40 oz R12; again if you have only 24 oz with a 250psi high at 81F, you have air.

[88911coupe]

Charlie, thanks for the suggestion...all your assumptions are in line with my scenario. I'm baffled how I could still be getting air in system but obviously that may be the case. I was very careful to purge the lines before adding the coolant but maybe I'm not purging enough...l let r134 out for about 3-4 seconds, is that enough? When I pull vac it appears to hold as far as I can tell. Not sure if this matters but I noticed my gauge read 3-4 lbs when disconnected and had read it needs to be adjusted to zero, which I did. That may be irrelevant but thought I'd mention it. This is about the 3rd time I've pulled vac so would think I've gotten all the air out but maybe not?

[kuehl]

Let's start with the vacuum equipment.

1) A good vacuum pump, fresh vacuum oil.
2) A good gauge set, with focus for the moment on the low side gauge.
When the gauge set is at ambient pressure, not under vacuum, no refrigerant,
the low side should read exactly on the Zero "0", not on +1 or -1 inches of mercury.
I prefer digital gauges however for a DIY that might be expensive, then again if you are spending hours with $50 analog set that is inaccurate it might be worth the investment, and I prefer a 4 valve service set, separate lines and valves for low, high, vacuum and refrigerant charge.
3) Before you pull a vacuum your pump should be able to down to -30 inHg in most cases, at sea level, in a matter of seconds. I'm at 500ft above sea level and my 15 year old 6cfm pump with used oil has no problems.




4) The best way to 'purge' service lines is to pull a vacuum on the refrigerant line first (no refrigerant can attached or if you have one make sure the valve is closed). Next method would be to liquid purge the line, but you have to be careful not to get liquid refrigerant on you or in your eyes (safety glasses). And you have to be careful not to 'liquid' slug the compressor with that liquid.