A/C issues

[gixxer750]

ok, my car has never had an air cond compressor for the entire time that I owned it. When I bought the car, it was simply not included. The lines were plugged and tapped off.

I recently aquired an AC compressor, and did the install

I replaced all o-rings in the system, replaced the dryer, put flush through the system and blew it out with my air compressor. I pulled a vacum on it, and it held for 2 hours. I then charged the system to TRSM specs using gauges and a 30lb drum of 134A.

The problem is, I don't know where to hook up the one wire plug coming off of the compressor. I found a power source to run the compressor for the charging. I used the blue wire on the two wire plug hanging down close to the A/C compressor. The compressor I got has a spade terminal on the wire, but no plug around it. I assume that the correct plug on the car for this is the small white single terminal plug between the battery and the fuse block. It is sticking out of a taped harness about 1-2 inches. The compressor wire reaches it perfectly.

When I plug into this, and set A/C to max, I get nothing. The compressor doesn't run at all. I have no voltage at this wire.

I also tried to jumper both high pressure switches on the passenger side fender wall.... didn't do anything either.

I have read the entire A/C section of the TRSM.

Any suggestions on where to start looking? It blows ICE cold when hooked up directly. I would like this to work, because the defogger works sooo much better, and we have really warm days here during the winter on occasion.


So, any suggestions on what to look to first?

 

[gixxer750]

um, bump

 

[Halsupramk3]

that wire is the one that will receive 12 volts when you turn on your a/c. There is one wire coming out of the loom under the fuse box at the battery. this goes to a relay that i think is in the fuse box that will supply 12vlts to the a/c clutch.

There is a 25 amp fuse in the passenger side kick panel thats right passenger side kick panel that supplies power to the clutch. If that fuse is blown your a/c will not work. I think there is another fuse in the drivers side too maybe. Be sure the wire coming out of the clutch is grounded to your a/c housing which will ground thru the a/c mount. That single wire just supplies 12 volts to the clutch and grounds out the housing of the a/c. Sounds like it is grounded.

 

[gixxer750]

yep, its got a good ground... you know, I checked the fuse in the drivers side kick panel, but not the passenger side.

on a side note, Hal.... I don't like this cold weather. traction problems in 3rd gear.

 

[gixxer750]

fuse is good.... anyone else have ideas?

 

[jetjock]

There should be a two pin connector for the compressor clutch. Look for it exiting the harness that is located directly under the fuse box. It's a light blue wire as I recall. Comes from the AC clutch relay which is also located below the fuse box.. The other wire (light blue/red) in the connector goes to the condesor fan relay as a feed for the fan. Check the 10 amp AC fuse and the 15 amp CIG fuse. Check to see if the dual pressure switch is closed. The ambient temp needs to be higher than 50 F too. Also check the AC magnet clutch relay. It should click when the AC comes on.

R134? I would've stayed with CFC 12. 134 will work but it has some issues. I hope you used the correct oil and adjusted the charge level for 134. At least you were smart enough to avoid something like Freeze 12.

 

[mrnickleye]

What year car? Turbo ? I will look at my '89 n/a tomorrow and see what I can come up with.

I am a tech, and have done a/c work on/off for 20 years.

The 2 switches on the high pressure line along the passenger side frame do this:
1 completes the circuit for the little fans to come on when the pressue gets high enough (warm temps).

The other cuts off the circuit for the compressor clutch if the pressure gets too high. When I converted to R134a, I had to put a jumper wire across the plug in that one to keep the compressor on. The high side will run a bit higher pressure with R134a.

The cooling effect with R134a is the same as R12 after its been on for awhile, and at highway driving. R12 cools 'quicker' for around town and stop and go, on and off driving. It is colder.

BTW...I live in the Mojave desert...= 100* in summer, and a/c at nite.:love:

 

[jetjock]

Me too, not only 609 but 608 Universal certified. It's why I would've stayed with R12. 134 works but is not optimum in a system designed for R12. Pressures are higher and that puts a strain on everthing. Important because at very high ambients with a small condensor fan and no vehicle movement the high side can get very high. Nor is the temp pressure curve of 134 the same as R12. It's just not as good a refrigerant as R12. Plus the condensor and evap are not as efficent when they're not designed to use 134. Details remember?

I don't know what he means when he says he charged to specs but if he used the R12 spec in the TRSM he screwed up. 134 charge should be 80% of R12 and adjusted from there. Using super heat is the best way to get the charge dead on but vent temps will do. As you said, R134 works (propane works too but you'd never use it) but as with all things MVAC it comes down to system longevity. Thats why I hope he changed to a good ester or PAO oil. Since the mineral oil used for R12 isn't miscible in 134 his compressor won't be long for this world once he gets it going. Good think he changed the receiver drier cuz the the dessicant in the old one wasn't 134 compatable if it'd been on there since the car was new..

As I said, at least he steered clear of Freeze 12 or the kits used to retrofit. They don't call them death kits for nothing. Btw, I'm sure you know that by jumpering your low pressure cut out you're risking compressor seizure if refrigerant is lost. Just a matter of time in a car so you'd better stay on top of the charge.

 

[gixxer750]

well, this car hasn't had a/c in years, and I would have put 12 in it, if I could find it, and it didn't cost 78 bucks a can. I put 2 cans of 134 A in, with a low pressure side pressure of 34 psi at 55 degrees ambient.

 

[csnow]

You are better off to pay $80 a pound for R12 vs the 134a. I have converted other cars and the 134a in an R12 system just won't pull down around town. I will never convert another car. My Supra still has R12 and will always have R12. Most A/C shops still have it if you ask.

 

[jetjock]

well, this car hasn't had a/c in years, and I would have put 12 in it, if I could find it, and it didn't cost 78 bucks a can. I put 2 cans of 134 A in, with a low pressure side pressure of 34 psi at 55 degrees ambient.

Blowing cold at 55 ambient isn't much of a way to test performnce but it should work OK. I'm just splitting hairs. As long as you're happy with it. 34 on the low side is a bit too high but close enough. The TXV in your evap was designed to work with R12. The main thing is did you use the right oil after the flush (a smart move btw). 55 ambient may be why your clutch won't engage. The ambient temp sensor (located near the hood latch) will keep the system off somewhere near that temp. Try holding your hand on it or use some hot water with everything hooked up the way it should be and see if the compressor starts.

Lots of cars have been converted without problem but some just don't like it. The Supra takes it well enough. I forget whether the Supra used barrier hoses stock but it's not a bad idea to change them when using 134. Not needed but not a bad idea. 134 is a smaller molecule but the stock hoses will have been coated with oil and should keep it from getting thru.

As for CFC12, you can buy it on ebay cheap enough. You need a 609 certification but that's easy to get online for $20. Course, it won't make you a real AC tech, you'll need to do lots more study for that, but it'll allow you to buy all the R12 you want. Or you can simply sign a statement it's for resale and cheat. The price of 134 skyrocketed last year. It's come down since then but is still spendy. If it gets too high that's another reason to stick with R12.

 

[gixxer750]

I used ester oil in the system. Also, my 134A was bought two years ago....I've got about 20 or so cans of it laying around that I paid about 4 dollars a can for.

I may put R12 back in it in the future, but for now, I'll try the 134. It has to be better than no A/C at all