A/C is not engaging?
Thread Starter
Melting Slicks
Joined: Jul 2006
Posts: 2,151
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From: Strongsville Ohio
A/C is not engaging?
all of a sudden, I went to turn the a/c on and I get nuetral air..I pulled into an autostore to check it out, I hit the auto button and then run to the engine bay and my a/c thingy next to my alternater is not turning. The belt is turning it but not engaging. I don't feel the lag I usually do when I turn the a/c on. Whats the first thing to check? i have never had A/C problems.
94 6spd
94 6spd
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
You can also check the low pressure cycling switch. Check to see if it is closed. Once connector is removed connect the two wires in the connector together and see if the compressor starts. (I assume you have no gauges)
Are any of you LEDs on the A/C control buttons flashing?
I have seen this problem where just by turning the key off and then re-starting everything can clear the problem. There might just be a hang up.
Did you check the A/C fuses? #1, 18, 43
Are you able to check those items?
After that, troubleshooting might become more difficult.
Are any of you LEDs on the A/C control buttons flashing?
I have seen this problem where just by turning the key off and then re-starting everything can clear the problem. There might just be a hang up.
Did you check the A/C fuses? #1, 18, 43
Are you able to check those items?
After that, troubleshooting might become more difficult.
Last edited by pcolt94; Oct 19, 2011 at 05:33 PM. Reason: changed fuse #
Thread Starter
Melting Slicks
Joined: Jul 2006
Posts: 2,151
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From: Strongsville Ohio
I have not had time today to give it a good check. I knew about low freon would not engage compressor. I will check fuses and the switch..Its a C4 vette, before I had motor issues and everything else was GREAT, Now I have a new motor ad everything else is breaking. Hopfully its just a fuse or the switch, even better if its just freon.
The A/C button is not flashing, I do have freon gauges and will check the levels.
The A/C button is not flashing, I do have freon gauges and will check the levels.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
I have not had time today to give it a good check. I knew about low freon would not engage compressor. I will check fuses and the switch..Its a C4 vette, before I had motor issues and everything else was GREAT, Now I have a new motor ad everything else is breaking. Hopfully its just a fuse or the switch, even better if its just freon.
The A/C button is not flashing, I do have freon gauges and will check the levels.
The A/C button is not flashing, I do have freon gauges and will check the levels.
Since you cannot check it at this time while the compressor is running, you can only check the static pressure. Depending on your ambient temperature, anything above 90 would be normal. 80-90 might be OK. But if your down below 70, that might not look to good.
But low Freon might give you a flashing LED and poor cooling before it got too low to work normal.
So I'm guessing you Freon is going to be OK.
And since you had all that work done, start looking for bad connections at the compressor, relay, cycling switches and anything else related to A/C.
Thread Starter
Melting Slicks
Joined: Jul 2006
Posts: 2,151
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From: Strongsville Ohio
wow, went out and checked the fuses and they were good. I started the car, turned the AC on high then checked the psi with a gauge. 100+ PSI..... How the heck did it get this high? It was working just fine the other day and for the last month. It has been the same +- 10 degrees all month since I had my car back from the tuner. He said he topped the charge off to make sure it was good.
I over charged a car once I accident one time and the air didn't work neither, so this is why for sure.
I hooked the pressure gauge up and opened the valve at the end to let the pressure out. I did it a little for about 20 seconds at a time then closed it. I got it from 110 down to about 95..and it is seeming to not go down and freon stopped spraying out, I am just getting pressurized air now. Is there any way to fix this besides taking it to a shop. I know I am not supposed to let freon out in the air but come on.
I over charged a car once I accident one time and the air didn't work neither, so this is why for sure.
I hooked the pressure gauge up and opened the valve at the end to let the pressure out. I did it a little for about 20 seconds at a time then closed it. I got it from 110 down to about 95..and it is seeming to not go down and freon stopped spraying out, I am just getting pressurized air now. Is there any way to fix this besides taking it to a shop. I know I am not supposed to let freon out in the air but come on.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
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From: Orlando FL
I would stop letting Freon out, that’s obviously not the problem which is making the compressor not engage due to low Freon. 100 psi doesn't seem to be out of the ball park to me. It depends on what your ambient temperature is and if the car is hot.
I would think you have an electrical problem. Check the connectors, cycling switch and such.
I would think you have an electrical problem. Check the connectors, cycling switch and such.
Thread Starter
Melting Slicks
Joined: Jul 2006
Posts: 2,151
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From: Strongsville Ohio
100 PSI is not much? its tached out into the red zone. The tach shows anything over like 60psi is "danger"...I dont know where my switch is. I have a FSM and will dig for it tomorrow am. Low freon- wouldn't that make the clutch engage then not, and cycle. Car was 196 when testing and outside temp was 83
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Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
100 PSI is not much? its tached out into the red zone. The tach shows anything over like 60psi is "danger"...I dont know where my switch is. I have a FSM and will dig for it tomorrow am. Low freon- wouldn't that make the clutch engage then not, and cycle. Car was 196 when testing and outside temp was 83
My low side gauge goes to 120 and high side to 450. If you have real gauges, there's nothing that says danger. What are you looking at?
I don’t understand most of your post. Like what is tach and switch represent?
When the clutch engages, the low side will go down and cycle between about 23 and 46 for normal operation.
Thread Starter
Melting Slicks
Joined: Jul 2006
Posts: 2,151
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From: Strongsville Ohio
I am reading a gauge you get from autozone that comes with a can of refridgerant
My gauge only hooks into the high side ( skinny) nipple on the hard ac line. The lower line is a thicker nipple.
I don't know what gauges you have but most everyone I know has the same kinds as me.
http://www.autozone.com/autozone/acc...questid=923954
This gauge above is like the one I have and tacks out at 100 psi. My reading is 100PSI when my car is running with A/C on high at lowest temp while car is running.
I dont understand what is hard to understand..I just dont know why my reading is at 100 psi and he other 4 cars in my driveway are at 30-45 psi
My gauge only hooks into the high side ( skinny) nipple on the hard ac line. The lower line is a thicker nipple.
I don't know what gauges you have but most everyone I know has the same kinds as me.
http://www.autozone.com/autozone/acc...questid=923954
This gauge above is like the one I have and tacks out at 100 psi. My reading is 100PSI when my car is running with A/C on high at lowest temp while car is running.
I dont understand what is hard to understand..I just dont know why my reading is at 100 psi and he other 4 cars in my driveway are at 30-45 psi
Thread Starter
Melting Slicks
Joined: Jul 2006
Posts: 2,151
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From: Strongsville Ohio
the swtich as in Compressor switch or something someone or even you mentioned above in another post. Someone said " check the system with a gauge, check the compressor switch ect..I dont know where the switch is
Race Director
Joined: Apr 2002
Posts: 10,036
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From: Anaheim CA
There are two switches located in the refrigerant lines. One is the high pressure switch and one is the low pressure switch. Follow the metal lines and you will find them (near the passenger side wheel well).
I don't remember the details, but when I had a bad switch I pulled off the connector and jumped the two contacts together and the clutch worked. I can't give you more details than that because the diagrams and descriptions in my FSM don't match my car. They mention a vacuum switch that I don't have and don't show the pressure switches at all.
From your description of the location of the compressor, it sounds like you have a late model C4. I don't know how your setup works, but on my '86 the engine does not need to be running to engage the A/C clutch. It makes a pretty loud click when it engages and disengages so it's easy to tell if it's working or not.
I don't remember the details, but when I had a bad switch I pulled off the connector and jumped the two contacts together and the clutch worked. I can't give you more details than that because the diagrams and descriptions in my FSM don't match my car. They mention a vacuum switch that I don't have and don't show the pressure switches at all.
From your description of the location of the compressor, it sounds like you have a late model C4. I don't know how your setup works, but on my '86 the engine does not need to be running to engage the A/C clutch. It makes a pretty loud click when it engages and disengages so it's easy to tell if it's working or not.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
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From: Orlando FL
I know exactly what set up you are using now. It's a gauge attached to a can of Freon designed for basic consumer usage but it is not a real set of gauges as a A/C repair business would use.
You should only connect to the low pressure fitting which is the upper fitting (high pressure fitting which is lower) near the top of the evaporator box.
When the engine is running and the compressor turning, the readings will be in the 30s and 40s, what you are familiar with.
You never connect to the high side because when the compressor is running, the pressures are from approximately 150 to 250 (depending on conditions) and if you put that pressure in your can, it will blow up. Besides, with the R134 fitting on there, you should not be able to connect to the high pressure side.
I'm assuming since you have not been able to get you compressor to engage yet, when connecting you gauge you will read a high reading since the system is not pumping and that would be a static reading.
If you're going to service your cars A/C get yourself a real set of gauges and get rid of that thing you are using. Then learn how to use it properly.
This is a set of gauges referring to and an great price too.
http://www.harborfreight.com/a-c-man...source=linking
The low pressure cycling switch is near the low pressure fitting. It has 2 wires to it.
You should only connect to the low pressure fitting which is the upper fitting (high pressure fitting which is lower) near the top of the evaporator box.
When the engine is running and the compressor turning, the readings will be in the 30s and 40s, what you are familiar with.
You never connect to the high side because when the compressor is running, the pressures are from approximately 150 to 250 (depending on conditions) and if you put that pressure in your can, it will blow up. Besides, with the R134 fitting on there, you should not be able to connect to the high pressure side.
I'm assuming since you have not been able to get you compressor to engage yet, when connecting you gauge you will read a high reading since the system is not pumping and that would be a static reading.
If you're going to service your cars A/C get yourself a real set of gauges and get rid of that thing you are using. Then learn how to use it properly.
This is a set of gauges referring to and an great price too.
http://www.harborfreight.com/a-c-man...source=linking
The low pressure cycling switch is near the low pressure fitting. It has 2 wires to it.
Last edited by pcolt94; Oct 19, 2011 at 09:40 AM.
Thread Starter
Melting Slicks
Joined: Jul 2006
Posts: 2,151
Likes: 0
From: Strongsville Ohio
Thank you
I knew something wasn't matching up. I have never seen such high psi..But the system not cycling, that would make sense its a reading of static psi..Not true reading of when system is operating..Not false but not the reading I am looking for. I should get the good line set-up you posted above. The gauge and line I have only fits on one nipple so it has to be the correct one. Of course its pouring today. I took off work to get this figured out and I am inside cleaning the house now...Thanks again.
I knew something wasn't matching up. I have never seen such high psi..But the system not cycling, that would make sense its a reading of static psi..Not true reading of when system is operating..Not false but not the reading I am looking for. I should get the good line set-up you posted above. The gauge and line I have only fits on one nipple so it has to be the correct one. Of course its pouring today. I took off work to get this figured out and I am inside cleaning the house now...Thanks again.
Thread Starter
Melting Slicks
Joined: Jul 2006
Posts: 2,151
Likes: 0
From: Strongsville Ohio
I checked for voltage at the compressor which is next to the alternator. I grounded my voltmeter then used the positive pin and put it into the green wire connecter and got no voltage. I even tried the black wire to make sure. Seems A fuse is blown?
Anyone want to verify what I have checked is correct thing to do?
Whats next?
Anyone want to verify what I have checked is correct thing to do?
Whats next?
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
You're at the end of the line of the problem. The reason the clutch is not engaged is because there is no voltage to it which is a given. That what is missing and the voltage comes from the A/C clutch relay on the right side of car near surge tank on inner wheel fender.
The relays don’t go bad very much. The relay is probably not being turned on. But the process of getting the signal to it is a bit elaborate and comes from the PCM. The first and easiest thing to do is to jump out the cycling switch and see if the compressor starts.
You can also try to ground the green/white wire of the cycling switch after you have the connector off to see if the compressor starts.
Re-seat any connectors that might relate to the A/C. did you check fuses #1, 18, 43.
The relays don’t go bad very much. The relay is probably not being turned on. But the process of getting the signal to it is a bit elaborate and comes from the PCM. The first and easiest thing to do is to jump out the cycling switch and see if the compressor starts.
You can also try to ground the green/white wire of the cycling switch after you have the connector off to see if the compressor starts.
Re-seat any connectors that might relate to the A/C. did you check fuses #1, 18, 43.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
Likes: 206
From: Orlando FL
It is the higher switch with the 2 wires (green/white & black) neat the hood. That is the low pressure switch.
The lower unit is the high pressure sensor (not a switch) and it has 3 wires to it.
Reseat the high and low pressure connectors just to make sure.
The lower unit is the high pressure sensor (not a switch) and it has 3 wires to it.
Reseat the high and low pressure connectors just to make sure.