How to test a AC compressor (1 Viewer)

[Dieseler]

I have read snippets of jumping a 12v wire from the battery to the compressor to test if it works.
Can someone point me to where I jump the wire to for this test I see 2 wires on the top of the unit which one do I hit with the 12volts for the test.
I am not sure if it is the compressor not working or the button on the dash when I push the button in the light does not come on ... so before I pull the dash apart I want to test the compressor first then work back to the switch.

Any pics or videos or even hand drawings would be good also.

 

[1 Bad FN FJ]

There is two wire going into the compressor, use a test light to determine which is the ground. Then run a jumper wire over to the other. You should here a click with the engine off.

 

[Dieseler]

I want to jump it while the engine is running to see if the clutch engages will this do any harm...I can't see any harm if done for a short period just to see if it the compressor works or something else in the system is faulty.

 

[Wile E Coyote]

I want to jump it while the engine is running to see if the clutch engages will this do any harm...I can't see any harm if done for a short period just to see if it the compressor works or something else in the system is faulty.

Totally appropriate thing to do, just keep the time jumpered to 1 min or less at a time.

 

[Dieseler]

I put my glasses on today for another inspection and relized what I thought was two wires was actually one wire so am I correct to assume this is the power lead to the compressor either way I don't have power to that wire according to my voltage tester so early conclusion is I have low pressure and will try the 12 volt jump to see what happens fingers crossed.

 

[Wile E Coyote]

Yeah the two wire thing had me perplexed, too. Trace that wire towards the firewall/battery area about 16" and you'll see a connector. Open that connection and jump from there to the battery with a 12ga jumper. Do this with the key off and watch/listen for the clutch to engage. It only moves a fraction of an inch. Also, before you dig too deep, check the fuse. Amplifier is another place to check. You need to rule out electrical before diving into much mechanical possibilities.

 

[Dieseler]

Where is the fuse I looked in the fuse box but do not see any A/C fuse positions in there I see a couple of big square fuse blocks but one is heater and the other was IGN but no A/C none of my FSM cover the 62 all earlier 60s and I dont have the drivers manual its in the other 62 four hours away.

 

[Wile E Coyote]

FSM A/C section shows ac fuse at position #11 counting from upper left to right...or 3rd on 3rd row said another way. Look in my sig line (when I post from a pc...posting from my phone using ih8 mud app right now and not sure what my sig line looks like) for the body and chassis fsm in pdf.

 

[Dieseler]

Thanks Wilecoyote I was looking at the fuse plate on my JDM 62 and it clearly shows the A/C fuse location it is a measly 10 amp obviously I was expecting it to be one of the bigger block style fuses.

 

[Dieseler]

Okay this is not simple as I thought it would be I picked up a R12 recharge/retrofit kit at my local parts store get home to find out the fitting in the kit for the low side is to big for the nipple on the compressor Grrrrrrr.
The guy at the parts store is stumped since the fitting is standard for all vehicles.
Any suggestions out there short of having my local Toyota dealer do it for a $150 flat rate recharge and that would be R12 recharge.
Wanted to keep this on the cheap the kit was only $44 included 2 refill cartridges and a sealant cartridge as well as the hoses and fittings even though one is the wrong size.

 

[Wile E Coyote]

Those kits are bunk, imho. There's more to switching from R12 to R134A. The system needs flushed, o rings changed, New receiver/drier, and vacuum applied.
More pointedly, why do you think a recharge of refrigerant is what you need? You've hooked gauges up and found an empty system?

 

[Coolstream]

Okay this is not simple as I thought it would be I picked up a R12 recharge/retrofit kit at my local parts store get home to find out the fitting in the kit for the low side is to big for the nipple on the compressor Grrrrrrr.
The guy at the parts store is stumped since the fitting is standard for all vehicles.
Any suggestions out there short of having my local Toyota dealer do it for a $150 flat rate recharge and that would be R12 recharge.
Wanted to keep this on the cheap the kit was only $44 included 2 refill cartridges and a sealant cartridge as well as the hoses and fittings even though one is the wrong size.

With R12 systems, the low-side fittings are always 1/4" male flare. If the threaded fittings on your compressor are not the same size, it's the high-side that is the smaller (3/16") port. There is usually an "S" for suction, stamped near the fitting on the body of the compressor. The easy way to tell is to follow the hose from the firewall-the big one, and that's the low pressure side. Hooking up a can to the high-side can blow up the can while you're holding it-not good!

 

[Dieseler]

Wilecoyote I am assuming it is low I dont have gauges to test it and looking through the view glass it looks to be lacking in fluid I jumped the compressor while engine running and the clutch engaged ...no squeeling or strange noises checked the fuse it was good I figure for 40 bucks add a cartridge and see what happens.

Coolstream the kit I bought has the big fitting marked as H and the small as L assuming the Low side lines are small and I dont see any markings on the compressor nor the caps my thinking would be the small compressor fitting that would be the low side.
.

Can someone clarify for me which nipple I am to use the small one closest to the fender or the larger one next to the engine.
I have attached a picture since everyone likes pictures the red cap is the small threaded fitting closest to the fender the black cap is the larger closest to the engine no markings after further inspection with my glasses on and a LED light shining up the area.

 

[Coolstream]

The low side is the larger cap, nearest the engine. Toyota and other manufacturers used a smaller, 3/16", thread on the high side to avoid hooking up to them incorrectly. When you hot-wired the compressor, did it blow cool or cold air out the vents? There is a low pressure switch near the evaporator that will prevent voltage from going to the compressor if the system is low. Instead of converting to R134a, why not top it off with R12 and avoid the hassle of retrofitting?

 

[Dieseler]

Thanks Coolstream when I jumped the compressor I was just checking to see if it would engage which it did I did not run it long enough to check for cool air flow cause I did not want to over run the compressor if it was low on fluid. Tomorrow I will run the test again and see if it is blowing cooler than the ambient blower air if so then its back to the part store to buy the kit I returned today and load one canister of sealant and one of R12 if there are bubbles in the sight glass I will add the second canister of R12.

 

[Wile E Coyote]

I personally would avoid using stop leak/sealant and adding refrigerant when you don't know the current charge (unless you know it's zero). Too high a charge could equal bad things.

 

[Elbert]

you need to find someone local with a set of R12 ac gauges and knowledge of the ac system so you can get things figured out.

Don't you have a sight glass on the dryer?

Generally the compressor will not engage if freon charge is low...of course you can hot-wire it as described.

If you hot-wire/jump the compressor pay attention to if you see bubbles in the system while looking at the dryer sight glass (engine running / compressor engaged). I would not run the compressor very long to make that determination.

Best bet is to find a local shop that works on A/C

 

[Dieseler]

So bottom line is today after accessing the low end line had no to min pressure in it and the sight glass did not show any signs of fluid or bubbling when jumping the compressor while engine running I went for it and added 2 canisters of R12.
After charging a can into the system and fluid was apparent in the sight glass I then unjumped the compressor and plugged the lead back together and whaala the compressor ran on its own and the air coming out is alot cooler than when I started the charging it is not at max cool but I can live with the way it is now.
The R12 has a dye in it so if the system leaks out on me I can hopefully trace it unless it is in the heater box which I am hesitant to take apart to trace a leak.

 

[Elbert]

old school r12 check for freon charge with sight glass method.

start engine engage A/c ....hopefully the compressor does engage and the temp is cooler.

Observe sight glass while engine running, set on max cold, after waiting 5-10 min for system to pass general (hey its working stage).

Bubles in the sight glass generally show a low freon charge.

The appearance of liquid is fine (looks like clear water)...

When fully charged the system should be clear (freon is clear) and very few bubbles if any.

 

[Wile E Coyote]

If there was moisture in the empty system, it will react and form an acid that will damage components over time.
If a leak presents itself soon and you are compelled to dig back in, consider renting a manifold gauge set and a vacuum pump for round two. Know that the schrader valves at the service ports (just like tire valve stem cores) go bad and are a very common source of leaks along with the compressor front seal.

www.aircondition.com if you want to learn more about ac operation and service.