A/C Pressure Switch...Which wires to jump to test compressor clutch????
06-18-2007, 03:34 PM
#1
A/C Pressure Switch...Which wires to jump to test compressor clutch???? Hey everyone. First...I have an 87 TA that I did a 99 LS1 swap on. I also used EVERY piece of the 99 LS1 a/c system. Bought new drier since the other was opened for awhile, and replaced all the seals in the whole system. I want to get it charged, but before I go through the trouble of setting up an appointment and all that...I have a question or two.
1) I want to make sure all my wiring is good, because I havent tested the system yet. SO Iwant to jump the pressure switch to make sure the clutch will engage when its supposed to. Only thing is, there are three wires instead of the usual two. I heard of a nother guy tryin to jump these and shorted some weird stuff out. Which two jump the switch?
2) If I get some cans of 134 from autozone or something, and start to put them in, will this hurt anything when it comes time to pull a vac. and have it charged by a professional? I dont mind wasting a couple cans of 134 to check the system out...but I do mind wasting the money it costs to have someone else do it only to have it not work.
Thanks in advance for any help!
Justin
1) I want to make sure all my wiring is good, because I havent tested the system yet. SO Iwant to jump the pressure switch to make sure the clutch will engage when its supposed to. Only thing is, there are three wires instead of the usual two. I heard of a nother guy tryin to jump these and shorted some weird stuff out. Which two jump the switch?
2) If I get some cans of 134 from autozone or something, and start to put them in, will this hurt anything when it comes time to pull a vac. and have it charged by a professional? I dont mind wasting a couple cans of 134 to check the system out...but I do mind wasting the money it costs to have someone else do it only to have it not work.
Thanks in advance for any help!
Justin
06-18-2007, 04:04 PM
#2
I doubt anyone will respond so here goes. This is an active sensor so that is why it has three wires.
One is a reference. It has 5 volts whenever the car or AC is on.
The other is a ground.
The last one is the signal wire.
I don't remember which is which. I can find out without the aide of a manual though. The one that has 5 volts when you turn the AC on is going to be reference pin. The one that has continunity with another pin on the TPS/MAF connnector is the ground. The ground is shared with one of those other connectors. The last one will be your signal wire.
The AC clutch will only activate when the pressure sensor switch seeing a range of voltage values. Too low or too high and it will not work.
You could try putting an adjustable resistor in there and dialing it around.
Maybe if I get bored later I will see what resistance my pressure sensor is reading.
One is a reference. It has 5 volts whenever the car or AC is on.
The other is a ground.
The last one is the signal wire.
I don't remember which is which. I can find out without the aide of a manual though. The one that has 5 volts when you turn the AC on is going to be reference pin. The one that has continunity with another pin on the TPS/MAF connnector is the ground. The ground is shared with one of those other connectors. The last one will be your signal wire.
The AC clutch will only activate when the pressure sensor switch seeing a range of voltage values. Too low or too high and it will not work.
You could try putting an adjustable resistor in there and dialing it around.
Maybe if I get bored later I will see what resistance my pressure sensor is reading.
06-18-2007, 05:51 PM
#4
Ok..messed around alittle. first...thanks for the info. I was looking at the wiring diagram, and it didnt look like it was a simple jump procedure like the older two wire ones were.
I put the required amount of oil in when I had the system open.
I tried putting 134 in it tonight. good news is, the compressor kicked on and sounds quiet and seems to be working. The drier is getting ice cold and sweating. The air from the vents isnt turning cold, but i didnt expect it to since I only got less than a can in before the dispenser broke.
Here is the bad news. Upon shutting the engine off, I can hear a hissing leaking sound from over near the evap. area. I cant locate the leak. I used a UV light since the 134 had leak detector in it. No luck. I tried spray soapy water around all the fittings while it was hissing...no luck. So...either I have a leak inside the evap box in the evap core itself, or there is a leak down by the compressor
If its the evap then fine. Ill replace it no biggie. If its down by the compressor...Im gonna be ticked because that isnt a small job to get that thing out.
That is...I dont think the hissing noise is normal...
Im going to try to do my best to track the leak down if it is one. Advance owes me a can of 134 since the crappy dispenser broke before the can was even half empty. So Ill just use that to "waste" on leak detecting.
J.
I put the required amount of oil in when I had the system open.
I tried putting 134 in it tonight. good news is, the compressor kicked on and sounds quiet and seems to be working. The drier is getting ice cold and sweating. The air from the vents isnt turning cold, but i didnt expect it to since I only got less than a can in before the dispenser broke.
Here is the bad news. Upon shutting the engine off, I can hear a hissing leaking sound from over near the evap. area. I cant locate the leak. I used a UV light since the 134 had leak detector in it. No luck. I tried spray soapy water around all the fittings while it was hissing...no luck. So...either I have a leak inside the evap box in the evap core itself, or there is a leak down by the compressor
If its the evap then fine. Ill replace it no biggie. If its down by the compressor...Im gonna be ticked because that isnt a small job to get that thing out.
That is...I dont think the hissing noise is normal...
Im going to try to do my best to track the leak down if it is one. Advance owes me a can of 134 since the crappy dispenser broke before the can was even half empty. So Ill just use that to "waste" on leak detecting.
J.
06-18-2007, 07:37 PM
#5
If you put only a couple of cans in it will get sweat without being cool in the cabin like you said. That's normal. I got a huge propane looking 134 can and it look a while for the AC pressures to come up.
Maybe look for oil around the compressor to see if it is leaking? Do you got gauges? Come back tommorow and see where your pressures are at.
I know pulling the compressor in a 2002 is kinda annoying if you don't have a lift. In a conversion oh boy I don't want to know!
Maybe look for oil around the compressor to see if it is leaking? Do you got gauges? Come back tommorow and see where your pressures are at.
I know pulling the compressor in a 2002 is kinda annoying if you don't have a lift. In a conversion oh boy I don't want to know!
06-18-2007, 08:31 PM
#6
Haha. Thanks for your help man. I didnt even get two cans into it. I have acess to a vacuum pump, a manifold set, and a big can of 134. The only reason I went through all this tonight was just to make sure the system functioned. I didnt want to waste my time pulling vacuum and using up my buddy's 134 if the compressor wasnt even going to work.
So Im going to leave it for now. I want to pull the top of my HVAC box and seal around the evap core better. I KNOW for a fact that most of the blower air is going around the evap. Which will of course not make real cold air. I figure the air would rather go around the evap than thru it...easier flow.
As for the hissing/leaking... I was wondering if you would do me a favor. Since you were willing to go out and check the resistance on your pressure switch, I was wondering if you wouldnt mind doing a simple little observation type test for me.
Can you fire your car, turn the A/C on max, let it run for a minute or something. Then shut the car off. As soon as you shut it off, walk over to where the lines from the drier connect to the evap tubes. Listen and see if you can hear hissing.
I went over and tried this on my mom's 97 Grand Cherokee. The A/C blows cold and has NEVER been serviced and doesnt leak. It actually hisses worse than my car and sounds like fluid is bubbling out. But no issues. The sound is coming from the same area where the orifice tube is installed. Im just wondering if its normal for an A/C system. Even my house A/C (window unit) will hiss alittle after its off.
If you can check that out Ide really appreciate it! Ill definetly post up after I get a vac pulled on it and put the gauges on it. And again, thanks for the feedback!
Justin
So Im going to leave it for now. I want to pull the top of my HVAC box and seal around the evap core better. I KNOW for a fact that most of the blower air is going around the evap. Which will of course not make real cold air. I figure the air would rather go around the evap than thru it...easier flow.
As for the hissing/leaking... I was wondering if you would do me a favor. Since you were willing to go out and check the resistance on your pressure switch, I was wondering if you wouldnt mind doing a simple little observation type test for me.
Can you fire your car, turn the A/C on max, let it run for a minute or something. Then shut the car off. As soon as you shut it off, walk over to where the lines from the drier connect to the evap tubes. Listen and see if you can hear hissing.
I went over and tried this on my mom's 97 Grand Cherokee. The A/C blows cold and has NEVER been serviced and doesnt leak. It actually hisses worse than my car and sounds like fluid is bubbling out. But no issues. The sound is coming from the same area where the orifice tube is installed. Im just wondering if its normal for an A/C system. Even my house A/C (window unit) will hiss alittle after its off.
If you can check that out Ide really appreciate it! Ill definetly post up after I get a vac pulled on it and put the gauges on it. And again, thanks for the feedback!
Justin
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06-19-2007, 07:09 AM
#8
OK....thats encouraging.
I tried the a/c this morning. It blew cold for a second, then just cool. So obviously it didnt leak out. Another thing I was thinking...if it was truely leaking, it wouldnt make that hiss each time i shut it off. It would just leak out and be done. So Im thinking its just a noise the a/c is making. Could be because its low on charge too.
Another thing I was wondering... I have an ASP underdrive pulley. I wonder if that is lowering the compressor's efficency during idle...? Maybe I should bump up the idle speed just a tad during filling. It idles at 900, so maybe bump it to 1000. I wont know until next week because I need to seal up the box yet.
J.
I tried the a/c this morning. It blew cold for a second, then just cool. So obviously it didnt leak out. Another thing I was thinking...if it was truely leaking, it wouldnt make that hiss each time i shut it off. It would just leak out and be done. So Im thinking its just a noise the a/c is making. Could be because its low on charge too.
Another thing I was wondering... I have an ASP underdrive pulley. I wonder if that is lowering the compressor's efficency during idle...? Maybe I should bump up the idle speed just a tad during filling. It idles at 900, so maybe bump it to 1000. I wont know until next week because I need to seal up the box yet.
J.
06-19-2007, 09:09 AM
#9
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mine hisses for about 3-5 secs after i turn it off. Its been ice cold for the past 2 weeks now. And its been in the 90's for those two weeks. If it was leaking i think it would start to get a little warmer.
