A/C clutch electric schematic

[Andyrose]

My clutch on AC not engaging even when I apply 12 volt to terminals. Why two terminals or conductors at plug-in? 1989 6 cylinder 4x4.

is there a schematic for AC switch fuse and wires? Where? 10 amp fuse okay no juice getting to plug in on clutch/compressor

 

[black_demon69]

here you go

 

[RonD]

The clutch on the AC compressor is an electro-magnet, it needs 12v and a ground to work

One wire will already be a fixed ground(black wire), so you just need to add 12v
Jumper from battery positive is fine, engine doesn't have to be running, key doesn't need to be on
If you don't see it engage/move in then replace the clutch

Its not hard to do but there are step to be taken and you DO need to shim it correctly when installing the new clutch
Several videos on how to do this

Most common issue for Clutch not working is that the system has a leak and pressure is too low
AC systems have pressure switches in the lines, if pressure is too low then it cuts 12v to clutch, so you don't burn up compressor if there is low pressure
Adding fluid doesn't help if there is a leak

 

[Andyrose]

Thank you for information. I will likely try to add some coolant and also take off and inspect clutch

 

[black_demon69]

Be careful not to over charge seals get blown that way. Also I recommend getting a gauge set and DO NOT USE ANY R134A WITH ANY SEALER IN IT. And only charge on the suction line. Would also be good to change valves in both service ports. And get a vacuum pump as well to pull a vacuum to remove moisture from the system also aids in getting r134a into the system.

 

[Andyrose]

So, do not use any of these? I thought I could read pressure with a tire air pressure gauge...not same.

 

[Curious Hound]

You need a more accurate gauge. A set of A/C system gauges guves accurate readings fir the high pressure and low pressure sides of the system. The ideal pressure changes depending on Ambient temperature.

some of what blackdemon said only applies if your system is completely empty and you are starting over. Products with sealers in them could cause obstructions in the system and cause more problems.

 

[Andyrose]

Found some R22 in a 3lb. Couldn’t I just top off the system once each spring? Tested clutch off vehicle and works fine. The pressure must just be a bit low, it would be nice to just top off?

Andy

 

[CrabGuy]

Don't use R22 in any vehicles AC system, that's for home AC and freezers. Your original system was R12; that stuff is as rare as unicorn teeth and incredibly expensive. You can convert to R134 but it requires a lot more than just dumping a can of AC Pro into the system. Not to be rude but if you aren't familiar with pre R134 AC systems find someone that is.

 

[Andyrose]

Update the early refrigerant is over $60/lb. going to convert to R134A. Check my steps,

1evacuate old refrigerant.
2 remover schraeder type valve.
3 remove each fitting to coils next to radiator.
4 replace O rings with nitra-bundle o rings.
5 attach adapter to for R134A cans,
6fill correct amount/pressure

 

[CrabGuy]

There is a lot of info online concerning the conversion. The most important one you are missing is a complete flush of the old system. A quick excerpt from one source is: A retrofit can be done one of two ways. The first is to follow the vehicle manufacturer recommended retrofit procedure. This generally involves removing all the old mineral oil from the system, replacing the accumulator or receiver/dryer with one that contains X-7 desiccant, replacing O-rings (if required), installing or replacing a high pressure cutout switch (which many shops seem to forget), changing the orifice tube or expansion valve (if required), then adding the specified PAG oil and recharging the system with R-134a. On some applications, installing a more efficient condenser may be recommended for improved cooling performance. After the modifications are made, the system is recharged to about 85 to 90% of its original capacity with R-134a.

I've done several conversions on older German cars and the systems never work as well as R12 unless a larger condensor is added; even then the results can be disappointing. You really need a vacuum pump (for evacuation and especially to check for leaks on your replaced components) plus an AC manifold set to do it right IMO or you are throwing good money after bad.

 

[97RangerXLT]

@CrabGuy uy has got it right. Not as simple as you think. You need to flush the system and the fill will be different for 134a vs 12. You also need an oil compatible with both r12 and 134a. If you put oil for 134a only in it you will trash the system.

Also replace the hoses with a barrier style hoses as 134 will leak through your old hoses. Consider replacing the evap and condenser vs trying to flush it.

I did a writeup on a/c system resurrection on here that takes you through most of what you need, but mine was a 134a system to begin with. Once you have it all back together you need to pull a vacuum on it for at least an hour and it needs to hold that vacuum before putting your oil and refrigerant..

Check my writeup on it for details like air temp pressure charts and proper tools needed

AJ

 

[Andyrose]

Wow, thanks for all the great info. So I went and talked with counter guy at NAPA auto and he said, oh yeah you can add 134a to an R12 system no problem. Then he tried to sell me the adapter kit, a hose to canister and canister of 134a. I am like thinking something does not add up here.

So searching on the web for R12 there is a product, by envirosafe Www.es-refrigerants.com. They have a product on line in a 4 oz can R-12, with hose for, like $18.50. I ordered a can because that is pretty low risk to see if I can just get the low pressure switch activating and compressor operating. But, they also sell an internal oil....should I use that also? Little skeptical to use the stop leak, but with the oil maybe soften or seal the o rings? Just trying to think outside the box on a limited budget.....

 

[CrabGuy]

Again, I feel think you have to think this out a bit better. Restoring a failed R12 system without doing it right usually has a low return on investment. Even if you can get the compressor to kick on, the old system obviously had leaks and needs to be opened and repaired. I've used an R12 substitute (Freeze 12) with very poor results including a seized compressor on my old Q45. There's just too much to take into consideration before you start looking for shortcuts. It's not like adding emergency coolant just to get you home from a failed HG; that works but the HG is still bad and needs to be addressed. Sorry if this sounds preachy.

 

[black_demon69]

if converting from 12 to 134 and not replacing the whole system IE flushing the condenser and evaporator and draining the compressor. you will need to use ester oil NOT PAG (because you will never get all the mineral oil out) if replacing the whole system then PAG oil is what you want (because no miner oil is in the system) If you have never done it do alot of reading and ask alot of questions or you WILL BE doing it all again.