94 AC issue
Thread Starter
Melting Slicks
Joined: Aug 2001
Posts: 2,089
Likes: 12
From: Port Saint Lucie, FL
94 AC issue
My 94 started a new problem the other day. Up until this point the AC has worked great and never given me any issues in the 8 years I have owned the car. That being said, I have not done anything with it other than adding a can of refrigerant to it a couple years ago. My first thought was maybe this was the problem again, but you can't add it if the compressor isn't engaging.
Problem is, sometimes the AC blows cold, sometimes not.
I have noticed that sometimes I can turn the climate control "OFF" and then back to "AUTO" and it will start blowing cold. When it is not blowing cold, the clutch on the AC compressor is not engaging.
Any clues what to check?
Problem is, sometimes the AC blows cold, sometimes not.
I have noticed that sometimes I can turn the climate control "OFF" and then back to "AUTO" and it will start blowing cold. When it is not blowing cold, the clutch on the AC compressor is not engaging.
Any clues what to check?
Safety Car
Joined: Jun 2006
Posts: 3,629
Likes: 28
From: FL
It may still simply be low on refrigerant, the system has a low pressure switch that prevents compressor operation when the charge is lost. Newer systems are often charged through the high side by professionals using charging stations which does not require the compressor to be running
You can jumper the low pressure switch to charge through the low side, after adding a small amount the compressor should continue to run after reconnecting the switch. You may want to add some dye when topping off refrigerant, sounds like you have a slow leak, good luck.
You can jumper the low pressure switch to charge through the low side, after adding a small amount the compressor should continue to run after reconnecting the switch. You may want to add some dye when topping off refrigerant, sounds like you have a slow leak, good luck.
Thread Starter
Melting Slicks
Joined: Aug 2001
Posts: 2,089
Likes: 12
From: Port Saint Lucie, FL
I was wondering if I could jumper the green and the black wire on the compressor. I wasn't sure or not.
It just figures that since I decided to spend some money on the car (in the last 2 weeks, I have put new rims and tires, Car PC, and tint on the car) that now something else acts up. Should have just left it alone.
And hello toptechx6 from a neighbor also in Boynton Beach.
It just figures that since I decided to spend some money on the car (in the last 2 weeks, I have put new rims and tires, Car PC, and tint on the car) that now something else acts up. Should have just left it alone.
And hello toptechx6 from a neighbor also in Boynton Beach.
Burning Brakes
Joined: Dec 2000
Posts: 1,161
Likes: 0
From: Orangeburg, NY
Is ounds like you are just low on refrigerant. Turn the car on and turn on the a/c to max cool. Add freon on the low side of the a/c. The pressure from the can will carge the system up enough to engage the compressor. Usually, adding one can will take care of the issue you are having. If you want to be on the safe side, buy an a/c line with a guage.
Safety Car
Joined: Jul 2004
Posts: 3,835
Likes: 30
It may still simply be low on refrigerant, the system has a low pressure switch that prevents compressor operation when the charge is lost. Newer systems are often charged through the high side by professionals using charging stations which does not require the compressor to be running
You can jumper the low pressure switch to charge through the low side, after adding a small amount the compressor should continue to run after reconnecting the switch. You may want to add some dye when topping off refrigerant, sounds like you have a slow leak, good luck.
You can jumper the low pressure switch to charge through the low side, after adding a small amount the compressor should continue to run after reconnecting the switch. You may want to add some dye when topping off refrigerant, sounds like you have a slow leak, good luck.
Safety Car
Joined: Jul 2004
Posts: 3,835
Likes: 30
Is ounds like you are just low on refrigerant. Turn the car on and turn on the a/c to max cool. Add freon on the low side of the a/c. The pressure from the can will carge the system up enough to engage the compressor. Usually, adding one can will take care of the issue you are having. If you want to be on the safe side, buy an a/c line with a guage.
Safety Car
Joined: Jul 2004
Posts: 3,835
Likes: 30
I was wondering if I could jumper the green and the black wire on the compressor. I wasn't sure or not.
It just figures that since I decided to spend some money on the car (in the last 2 weeks, I have put new rims and tires, Car PC, and tint on the car) that now something else acts up. Should have just left it alone.
And hello toptechx6 from a neighbor also in Boynton Beach.
It just figures that since I decided to spend some money on the car (in the last 2 weeks, I have put new rims and tires, Car PC, and tint on the car) that now something else acts up. Should have just left it alone.
And hello toptechx6 from a neighbor also in Boynton Beach.
Safety Car
Joined: Jun 2006
Posts: 3,629
Likes: 28
From: FL
Da Mail Man is correct that it could be something more complicated, but A/C systems frequently act erratic with a low charge. The pressure remaining in the system is close to the low pressure cut off point which can cause the clutch to engage at times and not at others.
I have a set of gauges if you'd like to check the charge, send me a PM and we can get together.
Don't expect the worst until at least doing that, it may be no big deal.
I have a set of gauges if you'd like to check the charge, send me a PM and we can get together.
Don't expect the worst until at least doing that, it may be no big deal.
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Safety Car
Joined: Jun 2006
Posts: 3,629
Likes: 28
From: FL
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
If it was low, there would be a code and it wouldn't produce cold air when it is running. More problematic that it simply has a loose or intermittent connection at the low pressure switch. Disconnect and jumper the harness with a paper clip. If it runs and you get something in the 40's out of the vents, fix the connection at the switch.
Thread Starter
Melting Slicks
Joined: Aug 2001
Posts: 2,089
Likes: 12
From: Port Saint Lucie, FL
Instructor
Joined: Apr 2006
Posts: 215
Likes: 0
From: Conway AR
If you have the computer controlled HVAC, I'd check the controller head 1st. If it works (blows cold) sometimes, that tells you the hardware is OK. Soooo, look at the software,and the controller.
Just a thought-worked for me.
bill
Just a thought-worked for me.
bill
Safety Car
Joined: Jun 2006
Posts: 3,629
Likes: 28
From: FL
Just noticed a sentence in my 93 manual that states "A/C Programmer logic can be lost if the battery is reconnected with the ignition in the on position", is it possible that could have happened during recent work on the car?
The reset procedure seems to be, ignition off, disconnect negative battery cable for one minute then reinstall, you may want to try that first.
If that doesn't work, the control head should display a code itself as SunCr mentioned but I don't recall the procedure to enter diagnostics, may be in the owners manual, certainly in the service manual if not there.
Not questioning your advice SunCr, you are the resident A/C guru, but wouldn't a poor connection at the low pressure switch also cause a code to be displayed?
The reset procedure seems to be, ignition off, disconnect negative battery cable for one minute then reinstall, you may want to try that first.
If that doesn't work, the control head should display a code itself as SunCr mentioned but I don't recall the procedure to enter diagnostics, may be in the owners manual, certainly in the service manual if not there.
Not questioning your advice SunCr, you are the resident A/C guru, but wouldn't a poor connection at the low pressure switch also cause a code to be displayed?
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Code retrieval is in Tech Tips. A flashing LED would indicate a code. Given the fail safe built into the design, the compressor isn't going to engage if a code is set.
An open at the low pressure switch isn't going to set a code. The low pressure switch circuit is monitored for how often it opens and closes - not how long the circuit stays open or closed. That - in a cycling orifice system - is determined by the air temp, not the charge level. As far as system design and diagnostics are concerned, if the switch is open - it's because it's too cold for a/c operation.
Processor was programmed to recognize a rapid opening and closing of the low pressure switch circuit as one of the indicators of a low charge. It also looks at the pressure sensor return signal (high pressure) line, usually about 80 psi static or .8 volts, but more importantly, for a voltage rise or pressure increase when the clutch is energized.
An open at the low pressure switch isn't going to set a code. The low pressure switch circuit is monitored for how often it opens and closes - not how long the circuit stays open or closed. That - in a cycling orifice system - is determined by the air temp, not the charge level. As far as system design and diagnostics are concerned, if the switch is open - it's because it's too cold for a/c operation.
Processor was programmed to recognize a rapid opening and closing of the low pressure switch circuit as one of the indicators of a low charge. It also looks at the pressure sensor return signal (high pressure) line, usually about 80 psi static or .8 volts, but more importantly, for a voltage rise or pressure increase when the clutch is energized.
Safety Car
Joined: Jun 2006
Posts: 3,629
Likes: 28
From: FL
Code retrieval is in Tech Tips. A flashing LED would indicate a code. Given the fail safe built into the design, the compressor isn't going to engage if a code is set.
An open at the low pressure switch isn't going to set a code. The low pressure switch circuit is monitored for how often it opens and closes - not how long the circuit stays open or closed. That - in a cycling orifice system - is determined by the air temp, not the charge level. As far as system design and diagnostics are concerned, if the switch is open - it's because it's too cold for a/c operation.
Processor was programmed to recognize a rapid opening and closing of the low pressure switch circuit as one of the indicators of a low charge. It also looks at the pressure sensor return signal (high pressure) line, usually about 80 psi static or .8 volts, but more importantly, for a voltage rise or pressure increase when the clutch is energized.
An open at the low pressure switch isn't going to set a code. The low pressure switch circuit is monitored for how often it opens and closes - not how long the circuit stays open or closed. That - in a cycling orifice system - is determined by the air temp, not the charge level. As far as system design and diagnostics are concerned, if the switch is open - it's because it's too cold for a/c operation.
Processor was programmed to recognize a rapid opening and closing of the low pressure switch circuit as one of the indicators of a low charge. It also looks at the pressure sensor return signal (high pressure) line, usually about 80 psi static or .8 volts, but more importantly, for a voltage rise or pressure increase when the clutch is energized.
