85 A/C question

[gost]

Trying to pin down a faulty syst and could use some input. My A/C worked fine last summer then early fall nothing not even the blower blowing warm air. I know the freon escapes on these systems but would the blower fan (evap) function even if freon is low? I checked the drier sight glass and looks empty but is hard to tell in that fender well. The compressor clutch will engage when I first start the car and turn on the A/C but will then disengage in about 20 seconds. The front condenser fan will operate the same way, initially on then 20 seconds later off. Seems like some sort of lockout is happening. When I checked the blower with ign on and the blower switch on hi it was getting juice but not operating so switch should be OK and blower faulty?
I hate to do this work and find out that there is some kind of lockout mechanism when freon is low preventing the blower and other components from operating. Bentley's does not address this.

Thanks for your input. Gordon

[thunderdenton]

The blower does continue to work on my 1984. I am pretty sure the same thing happens for all the 1984 to 1989 so they can move in fresh air.

[nut11]

I just took the A/C system out of my 85 coupe but kept the blower. It does move a good amount of fresh air. Boxed all components up. 4 hour job. You lose weight, 60 or so lbs. and keep money for repairs not needed. Living in the NE makes A/C not really needed IMHO.

[Hugh R]

Don't know about your car, but most cars have a high-low pressure switch to prevent exactly what your experiencing. Its an inline switch usually on the receiver/drier with two wires attached. Or it may be inline on one of the lines between the compressor and the R/D. If you find it, you can bypass the switch with a jumper lead, just don't do it for very long!

[chgrec]

On my 84, I had the same problem and found it was the relay located in the smugglers box.....Once I replaced that, the blower fan started working again.....A/C still doesnt blow cold as the compresor clutch never kicks on. So I know the fan works independent of the compressor function....

Chris

[gost]

Nut11, it's tempting to just yank it all as you did especially that compressor, always in the way but I'm in the NE as well and it does get steamy hot here and I'm usually in the Carrera and the A/C was soooo nice to have plus the original equipment aspect of it all, like to keep her as she came.
Hugh, I will look into the pressure switch, that's a good call. Really I should charge the system up to make sure it does have freon but that's quite a few sheckles and would hate to evacuate to make other repairs and toss the dough out.
Chris, I was eyeing that relay but I tested the voltage to the blower at the harness disconnect and it had juice and wouldn't that be down stream of the relay rendering it operative? I'm not sure now. What do you think?
Thanks so much.

[Hugh R]

Gost

Several people I know have just added R134a oil (for an R12 conversion, ask an A/C auto parts place which oil) and charged with R134a and got satisfactory results. I put 134a in my 84 with an R12 compressor, and it works pretty well, I also added condensors and a new Receiver/Drier. 134a is about $10/lb versus R12 which is over $100/lb and you can do 134a yourself.

[chgrec]

Not sure with out looking at the wiring schematic again.....I figured since the relays are inexpensive and used lots of other places on the car, I would try it. If it didnt help, i could reuse the relay somewhere else. The local generic auto parts store had the relays in stock so it was an easy test.....

(My voltmeter broke a couple of months ago due to a poor placement of my hammer...made a nasty crunching sound when it died)

Chris

[chgrec]

I did a r134a conversion on my Alfa using an inexpensive kit from the generic auto part store and it worked great.
I plan to do the same to my 84 should freon be needed, once I verify the compresor clutch is working as it should........

Chris

[gost]

Hugh, I did not know that. Thought the compressor had to go. My problem would be evacuating the syst since that needs to be done first and then re-fill. I don't have the equip to do that or are you saying to just fill from this point up and mix the 12 and 134a since I can do that part myself?
Chris, I'm sure it served you well and have fond memories. My condolences. True, cheap part, just trying to save $ as I'm in a hole trying to claw out right now.
Thanks

[Hugh R]

If you have any pressure at all in the system (push on the low pressure fill valve and see if you get some Freon pushing out. If so, you shouldn't need to evacuate. Evacuation is (I believe) only to get the air out otherwise you can't put the refrigerant in, and to test when replacing parts to see if it is leak tight (i.e., to hold a vacuum for a 1/2 hour or so). Do a search on the boad for Jim Sims, he is an A/C God!

But yes, no reason you can't mix the two refrigerants, just get the R12 to R134a retrofit kit from Walmart, Autozone, Kragen, make sure you use the new oil charge (its a can like refrigerant), in fact I think you can buy the 134a with the oil already in it. Jim Sims says no need to change to barrier hoses, as the old oil will help seal the lines from the inside. The reason for the new oil is that 134a won't pick up the R12 oil and you'll damage the compressor.

[gost]

Got it Hugh. sounds simple enough and i will look up Jims posts as well. Hot weather will be here soon and with a triple black Cab the A/C is a blessing.
Regards,
Gordon

[RickM]

Consider some dye as well. You lost freon for a reason. While a small amount makes it's way out on it's own, over time, you likely have a leak somewhere.

Also, consider the Vent Bowtie removal. This will help increase airflow into the cabin.

[RickM]

Here's Don's excellent write-up on a center vent addition: No more Bowtie! My center vent kit

and more here... http://plumley.org/das_zoom/ac_vent.htm

[Jim Sims]

To convert an R-12 system with R-12 still in the system I recommend taking the car to a A/C shop and having the remaining R-12 pumped out and recycled. One might have them leak check the system then too. Do not mix R-12 and R-134a. I further recommend that the system be opened up at all the low spots (hose fittings) and drained of mineral oil, In addition, the condensers should be flushed and the receiver/drier replaced. The compressor should then be drained of mineral oil and this replaced with ester oil in the correct amount for the system. Any o-rings and seals in the system should be replaced with ones compatible (typically green or blue colored) with R-134a and the new oil. I also recommend installing a high pressure cutout switch on the output side of the compressor. Then the system should be evacuated with a good vacuum pump (40 micron or less) for three hours; it is helpful if the car is in the hot sun during evacuation to mobilize more of the water vapor so it can be pumped out. Check for leaks. Then fill with R-134a using a refrigeration harness to within the correct pressure range and by monitoring the cold output air temperature (when temp no longer falls then stop adding refrigerant). Back decklid should be down and the engine running while charging system. Wear safety goggles plus get experienced help if you haven't done this before.

[gost]

Thanks Rick, that post was chilly reading and an easy upgrade.
Jim, thanks are in order. I was sure it was a bit more involved than just adding 134a to the syst. I'm sure it will set me back a few $ but it sounds like the right way to do it. Don't want to loose the compressor.
By the way Jim any ideas/comments on my starting post? Does it sound like just low charge or is something darker lurking? Much apreciated,

Gordon

[Jim Sims]

I do not believe the 85's come equipped with a low pressure cut out switch; if there's one there it should be easy to find. It will likely be in the refrigerant lines near the compressor. I suspect what is the more likely problem is that the switch (in the console?) has failed or is failing (opens up under excess current). There is too much current being pushed through these switches (I know of one that melted) when the fans get old and start to bind and lock up. Your system could also have circuit breaker or relay that is opening up (my '76 uses a relay and a circuit breaker) when too much current is being drawn. First I would check your A/C electrical system; the refrigerant portion of your system may be fine. Check for a circuit breaker or relay. Try disconnecting the front condenser fan and see if that eliminates the compressor shutdown problem. If it does, the fan is failing and may eventually cause a front compartment fire if it melts its power wire. There is a fuse kit available to solve this problem.

[gost]

OK Jim, gives me a starting pont to work with.
Thanks again

[PatrickB]

Keep it simple! Of course check the relays, but the bottom line is that you probably have a slow freon leak... I did the R134 change 2 years ago. I had a slow annoying leak when the system was R12, that required recharging every 6 or so weeks. O)nly a half a pound was added, brining it just a hair over suggested max... Don't sweat the R134 change. I also just changed the fittings, and dumped in R-134. No problems for 2 years. My mechanic has done the change on several other 911's, and feels that the R-134 often will actually fill some leaks, or at least slow them down. I now get it charged twice a year. Always make sure that when the system is recharged, it gets filled to the maximum allowable level. With the R-134, 1/4lb. below max level makes about an 8 degree difference at the vent in my car.
PB

[gost]

Pat, I will get it running at least and if I'm out of 12 I will go to the 134. I last charged my AC in the summer of 2000 and it was working fine through the summer of '04 that's 4 years no problems. I know that Porsche designed their refrig lines to leak by placing pinholes in them. Don't ask me why, that was before the EPA would have killed them but the story I heard was to reduce pressure in all the spaghetti they used. Again don't know why you would need to vent 12 into the atmosphere.
I'll post my results as soon as I get my hands on a few relays.
Thanks

Gordon