ClassicCarl

I'm having a problem with my A/C compressor clutch not engaging. The electric fan cycles on properly when turned to the A/C setting is chosen. I know the compressor clutches are ok because it worked in the Jeep I took it out of. Also, when I directly wire the compressor to the battery, it engages instantly. The system is full of coolant so the low pressure switch is not the culprit. Fuses OK. I'm terrible with wiring so wondering if anyone has come across this. I'm thinking PCM ground, broken wire or the clutch relay? Idk haha

DFlintstone

Out of my league here. I'm pretty sure it has a standard SPDT relay, (diagram found in my sig.) which is often grounded by the PCM to activate the relay. Power is connected out the top from the bottom, when (allot less), goes in the right to, the PCM ground on the left.

Allot can be learned at a relay socket.
Does it have power right and bottom? Is the left being grounded? (to activate). Does jumping power to the top make it work? (Clutch in this case)

I just know the relay, not the AC!

Jaster343

How much R134 did you put in? Was the jeep running at the time? Did the compressor kick on at all during the fill process?

ClassicCarl

It was off. We charged it until it hit the specified weight in pounds of whatever it is. Used a machine to do it

Jaster343

Do you have a gauge to check the operating pressure of the AC system?

ClassicCarl

no unfortunately I do not :/

sycoglitch

System must be on to fill it up. See if you can get one of those do it yourself 134 cans. Add a lil but with AC at full blast and see if it engages

Oh and what year didn't you say your jeep was and what year you didn't get the AC from

Jaster343

The only reason i ask is because I had similar symptoms and it did ultimately wind up being the low pressure cut off. If you can get a gauge (the DIY cans of r134a come with one) then you could jump out the compressor and get a reading on the operating pressure of the system. The compressor has to be operating to get the working pressure of the system. Might be worth a trying.

sycoglitch

Those gauges are worthless on the cans. Always told me I had enough, used a real gauge and it was off.

Honestly best way to do the AC is to vacuum the system fully and let it hold at retard and then properly fill with refrigerant. Those can are only to top off a little bit of lost coolant but really you're not suppose to loose coolant from a sealed system.

Jaster343

I agree they are garbage, but a cheap way to determine if the system is to low to operate the compressor.

sycoglitch

BInGO, and this is what the OP needs to try AFteR he tells us his frickin years. I gave up my mind controls powers when I got married so unless he speaks he's ****. Outta luck. Iirc older jeeps didn't use 134.

mikerosa

On your A/C "dryer" there is a plug on the top of the tank. That is a low level shut off switch so the cluck won't burn out if there is no lubrication present.

Hook your A/C gauges with oil and freon 134 up on the "low" side pressure which pipes are bigger than the high pressure side.

With a paper clip, insert an end of the paper clip into each recepticale of the black plug. This will immediately "jump" your compressor.



As the compressor turns, it's will "suck" thru the low side and your freon and or oil will empty. Be careful to read how many finished pounds of freon you have so as to not overdo it and pops your seals.

I believe 32 pounds of pressure is about right when done.

If your condenser is filled with freon and the clutch won't turn, but it turns when you use the paper clip jump, you need a new shut off switch,,, $50 part or so.