Check AC compressor?

[avatar28]

Do these cars use a low pressure switch for the AC compressor? Mine won't kick on at all. I know somebody said it won't below a certain air temp but even above that it won't and it should for the defrost anyways right? It's going to be warmish and rainy this week. I'm going to need dry air to keep the window unfogged.

Short of taking it to a shop, what's the easiest way to check if the AC system is working at all? I suspect it has a leak somewhere, a lot of the metal part near the radiator cap is pretty rusty; don't know if that's normal or not (I will post a picture later if it will help). If it has a low pressure cutoff switch, I'm thinking I could add a can or two of refrigerant and see if it starts kicking on. How can I check the oil level of the compressor too? I don't want to add more if it already has enough.

 

[jmpSHO2nd]

Yes..

 

[rubydist]

it is called the 'a/c cycling switch' by the factory. it sits on top of the accumulator. you can jumper it temporarily to see if the compressor kicks on or not.

its a reasonable guess that it is low on refrigerant, but it is just a guess.

it could also be a bad clutch gap, bad wiring to the clutch, bad eatc, etc. if you jumper the cycling switch, you will know if its a pressure issue.

 

[TimboSHO]

My A/C compressor still kicked on with the defrost on days it was -15 out. So I don't think ambient temperature has anything to do with it.

You are either low on freon, it's not getting the command to turn on, or you have bad parts.

 

[avatar28]

My A/C compressor still kicked on with the defrost on days it was -15 out. So I don't think ambient temperature has anything to do with it.

You are either low on freon, it's not getting the command to turn on, or you have bad parts.

Yeah, I knew it should with the defrost at least. Slightly cooler dry air is MUCH better than warmer damp air for defogging the windows. Thanks for confirming that though.

 

[rubydist]

no, its not supposed to kick on the a/c at temps below around 10F - I don't recall the exact temp but I do know that at -15F it should not be running the a/c.

 

[TimboSHO]

no, its not supposed to kick on the a/c at temps below around 10F - I don't recall the exact temp but I do know that at -15F it should not be running the a/c.

Interesting. I didn't think it seemed right when I started the car and immediately the a/c compressor kicks on and the fan kicks on when it was that cold. Which temp sensor determines when it's too cold for A/C?

 

[jimtash]

Every time water has gotten on the CCRM conector on my car, the compressor and fan will automatically kick on. Problem is that it doesn't stop unless I disconnect the harness at the compressor and wait until everything is fully dry to plug it back in. The first time this happened, the lines ended up with a heavy coating of frost because the pressure switch didn't stop the compressor from cycling and I didn't know any better. Now I unplug the compressor whenever I know water will be in and around the CCRM.

You might want to try it OP. The CCRM has a lot to do with the AC system.

 

[pjtoledo]

Interesting. I didn't think it seemed right when I started the car and immediately the a/c compressor kicks on and the fan kicks on when it was that cold. Which temp sensor determines when it's too cold for A/C?

cold engine lock-out switch in the coolant line to the heater?


just pulled the 95 Helms out, page 12-00-14,,, below 7-10c or 45-50 f the refrigerant does not have enough pressure to activate the cycling switch, thinks its low on r134

so, what about the cold engine lockout???? not on all years??

did some more reading, cold engine lockout only prevents the cooling fan from operating until the coolant is warmed up enough to supply some heat to the cabin.

 

[rubydist]

So I looked it up, since I could not remember how it was supposed to know not to cycle the a/c when its cold out. Here is what the manual says:

"Ambient temperatures below approximately 50F during cold weather seasons prevents the a/c cycling switch from closing.
This is due to the pressure/temperature relationship of the rfrigerant and the requirement of the system pressure to reach the pressure required to close the a/c cycling switch contacts."

In other words, if your a/c cycles on when its below freezing, you either have the system over-pressurized, or your cycling switch is bad.

 

[TimboSHO]

cold engine lock-out switch in the coolant line to the heater?


just pulled the 95 Helms out, page 12-00-14,,, below 7-10c or 45-50 f the refrigerant does not have enough pressure to activate the cycling switch, thinks its low on r134

so, what about the cold engine lockout???? not on all years??

did some more reading, cold engine lockout only prevents the cooling fan from operating until the coolant is warmed up enough to supply some heat to the cabin.

So I looked it up, since I could not remember how it was supposed to know not to cycle the a/c when its cold out. Here is what the manual says:

"Ambient temperatures below approximately 50F during cold weather seasons prevents the a/c cycling switch from closing.
This is due to the pressure/temperature relationship of the rfrigerant and the requirement of the system pressure to reach the pressure required to close the a/c cycling switch contacts."

In other words, if your a/c cycles on when its below freezing, you either have the system over-pressurized, or your cycling switch is bad.

Things to check out when it gets warmer out!

 

[avatar28]

Say, uh, I tried to pull the wiring harness for the cycling switch off the top of the accumulator. The plastic just started folding back, like it was hot and melted. That's not supposed to happen, right? Guess I'm in for a new switch and wiring harness.