Need AC help

[Eric1971]

AC stopped working last week in my '95 EB, just blowing ambient temp air even when set to "Max A/C". Never had a problem before. Finally got around to investigating because even though I'm mostly sitting at home these days, it's getting too hot outside for no AC. Here's what I found...

1. Compressor clutch is not engaging, ever... well that will certainly keep the AC from cooling!
2. Pulled the power connector off the AC compressor clutch and checked with my multimeter and it's reading about 13.8V when the car is running and set to "Max A/C". 0V when AC is off, of course.
3. If I run power from the battery directly (reading 14.1V) to the clutch, it engages just fine.
4. When I got the clutch to engage, the pressure gauge was showing good charge level.

All that makes me think that the clutch connector is faulty. I found replacement connectors online, so it should be easy to try, I just feel like maybe I'm missing something or going down the wrong path. Any advice or ideas would be greatly appreciated. Thanks!

 

[crunchie_frog]

AC stopped working last week in my '95 EB, just blowing ambient temp air even when set to "Max A/C". Never had a problem before. Finally got around to investigating because even though I'm mostly sitting at home these days, it's getting too hot outside for no AC. Here's what I found...

1. Compressor clutch is not engaging, ever... well that will certainly keep the AC from cooling!
2. Pulled the power connector off the AC compressor clutch and checked with my multimeter and it's reading about 13.8V when the car is running and set to "Max A/C". 0V when AC is off, of course.
3. If I run power from the battery directly (reading 14.1V) to the clutch, it engages just fine.
4. When I got the clutch to engage, the pressure gauge was showing good charge level.

All that makes me think that the clutch connector is faulty. I found replacement connectors online, so it should be easy to try, I just feel like maybe I'm missing something or going down the wrong path. Any advice or ideas would be greatly appreciated. Thanks!

The first thing I would think would be either low pressure or the pressure switch being bad but you eliminated that, I suppose, by getting voltage at the clutch from the power connector. The only other think I could think of, besides a bad connector, would be the clutch is bad and the difference between the14.1 and 13.8 volts could be just enough to make it not work.

​

 

[Eric1971]

Good point on the voltage difference. I'll try connecting from the battery with the engine off and see if the clutch engages with 12.8V

 

[Eric1971]

Here's more clues...
- The clutch engages very strongly with 12V from the battery while the engine is off.
- It doesn't appear to be the connector. What seems to be happening is when I have it disconnected, I'm getting voltage on the multimeter, but when it's connected to the clutch, the voltage stops. I was able to access the back of the connector so that I could test the voltage while the connector was still plugged in.

So, what/where is the next point down the line to check? I already check/swapped the WAC relay and the AC fuse.

 

[crunchie_frog]

Here's more clues...
- The clutch engages very strongly with 12V from the battery while the engine is off.
- It doesn't appear to be the connector. What seems to be happening is when I have it disconnected, I'm getting voltage on the multimeter, but when it's connected to the clutch, the voltage stops. I was able to access the back of the connector so that I could test the voltage while the connector was still plugged in.

So, what/where is the next point down the line to check? I already check/swapped the WAC relay and the AC fuse.

Try jumpering the pressure switch. If it comes on then, either it is low on refrigerant or the pressure switch is bad.

 

[Eric1971]

Ok, I was just trying to do that... I found the low and high pressure switches. Do I just unplug and jump one wire to the other on the harness?

 

[crunchie_frog]

Ok, I was just trying to do that... I found the low and high pressure switches. Do I just unplug and jump one wire to the other on the harness?

unplug the low pressure switch, jump the two pins. If it runs, do not keep running it, just see if that makes it run. If so, it is either low on refrigerant or a bad switch, my guess would be low refrigerant.

 

[ThreeJs]

I'm guessing you have the EATC unit if it's an EB.
If pressure switches test good it may be the EATC unit.

 

[Eric1971]

I jumped both (separately) and neither did anything. I checked the voltage coming in and there was nothing on the low-pressure switch and about 5V on the high-pressure switch.

I found another thread where the guy had similar issues and traced it to "the Temp control sensor behind the glove box. It was stuck open, cleaned it and it worked. " I can't find that or find what it looks like.

I installed a new stereo back in January. I suppose just to be safe I could make sure everything is tightly plugged into the back of the fancy climate controls.

 

[crunchie_frog]

You should be getting voltage at the low pressure switch. The voltage to the clutch goes through this switch and there should be voltage, low pressure switch is closed when there adequate pressure/refrigerant. Do you have a wiring diagram, might want to google for one and see why you do not have voltage going to the low pressure switch.

 

[Eric1971]

Controls are plugged in fine. AC was in use and working consistently and fine up until last week, so I don't think my stereo install is to blame.

 

[Eric1971]

Definitely a learning experience, I did find a diagram though the wire colors are not exact. I figured out which wire was voltage on the LP switch, jumped it so that I got voltage on the HP connector, then I jumped on the HP connector and got nothing. Now the weird thing is when I tried running from the battery to the output wire on the HP connector, bam, the clutch engaged. But when I jump the HP connector, which is definitely getting full voltage in, I get nothing. Ugh... looks like I may have to see a pro...

 

[crunchie_frog]

Definitely a learning experience, I did find a diagram though the wire colors are not exact. I figured out which wire was voltage on the LP switch, jumped it so that I got voltage on the HP connector, then I jumped on the HP connector and got nothing. Now the weird thing is when I tried running from the battery to the output wire on the HP connector, bam, the clutch engaged. But when I jump the HP connector, which is definitely getting full voltage in, I get nothing. Ugh... looks like I may have to see a pro...

Well, I have a typical wiring diagram from my Haynes manual for this vehicle and it shows a 10 amp fuse and the AC ON switch as being the only things that break power to the low pressure switch. If you do not have voltage to the low pressure switch when the vehicle is in run, check your fuse and the AC switch. Good luck with seeing a "pro".

 

[Eric1971]

I did get voltage on the LP switch, I was just doing it wrong the first time!

 

[crunchie_frog]

I did get voltage on the LP switch, I was just doing it wrong the first time!

Okay, back to square one, if you are getting voltage to the LP switch but not getting voltage to the compressor clutch, you have either low refrigerant pressure or a bad pressure switch and when you jumper the two pins where there is voltage on the power connector to the LP switch, the compressor should run.

 

[1998Exp]

AC stopped working last week in my '95 EB, just blowing ambient temp air even when set to "Max A/C". Never had a problem before. Finally got around to investigating because even though I'm mostly sitting at home these days, it's getting too hot outside for no AC. Here's what I found...

1. Compressor clutch is not engaging, ever... well that will certainly keep the AC from cooling!
2. Pulled the power connector off the AC compressor clutch and checked with my multimeter and it's reading about 13.8V when the car is running and set to "Max A/C". 0V when AC is off, of course.
3. If I run power from the battery directly (reading 14.1V) to the clutch, it engages just fine.
4. When I got the clutch to engage, the pressure gauge was showing good charge level.

All that makes me think that the clutch connector is faulty. I found replacement connectors online, so it should be easy to try, I just feel like maybe I'm missing something or going down the wrong path. Any advice or ideas would be greatly appreciated. Thanks!

Edit: You already tried jumpering across the LP connector, and even across the HP one. I am not familiar with the '95. Do you have the EATC (automatic climate control) or is it manual? If EATC, the problem may be there Much simpler for manual, but I wouldn't trust the Haynes generic schematic -- look for the proper one for your model -- they are in the "Electrical and Vacuum Troubleshooting" booklet.
================================================================================================
Try disconnecting the low side pressure sensor connector (on the accumulator/dryer) and shorting across the two connector pins with a piece of wire. If the compressor now engages, you have low charge or a bad sensor. The sensor should read 0 Ohms above 44 psi. If it shows an open, it may be bad or you are very low on gas. I wouldn't trust the gauge on the gas bottle that they sell in the stores. If you are certain you have correct charge and the sensor is open circuit, it may be bad. They are cheap and easy to replace -- no need to discharge the system. There are other possibilities, like a bad relay (not sure where it is on a '95), bad high pressure cutoff, etc. You will need an electrical schematic to trace those.

 

[Gary Crist]

Just for giggles, can you hook the gauges back up, jumper
the clutch, run the car @ about 2K RPM and tell us the
readings.

 

[DeniseO30]

AC stopped working last week in my '95 EB, just blowing ambient temp air even when set to "Max A/C". Never had a problem before. Finally got around to investigating because even though I'm mostly sitting at home these days, it's getting too hot outside for no AC. Here's what I found...

1. Compressor clutch is not engaging, ever... well that will certainly keep the AC from cooling!
2. Pulled the power connector off the AC compressor clutch and checked with my multimeter and it's reading about 13.8V when the car is running and set to "Max A/C". 0V when AC is off, of course.
3. If I run power from the battery directly (reading 14.1V) to the clutch, it engages just fine.
4. When I got the clutch to engage, the pressure gauge was showing good charge level.

All that makes me think that the clutch connector is faulty. I found replacement connectors online, so it should be easy to try, I just feel like maybe I'm missing something or going down the wrong path. Any advice or ideas would be greatly appreciated. Thanks!

clutch will not engage if it is low on refrigerant, the most common cause of no AC vehicles,
gauges don't show level, they show pressure, what are your pressures and outdoor temperature ? is the only way anyone can help you, online. when you have the compressor bypassed and running a quick check would be a cold refrigerant line coming back from the evaporator, the discharge line into the condenser off the compressor should be too hot for you to touch. But not always, depending on outdoor temperature,
it is highly likely you are low on refrigerant.

 

[Belfairherb]

clutch will not engage if it is low on refrigerant, the most common cause of no AC vehicles,
gauges don't show level, they show pressure, what are your pressures and outdoor temperature ? is the only way anyone can help you, online. when you have the compressor bypassed and running a quick check would be a cold refrigerant line coming back from the evaporator, the discharge line into the condenser off the compressor should be too hot for you to touch. But not always, depending on outdoor temperature,
it is highly likely you are low on refrigerant.

 

[Belfairherb]

The one thing no one has checked is the wiring. Since the clutch engages when connected directly to the battery and not through the normal wiring harness, it looks to me like there is a wiring problem. Perhaps a bad connection somewhere upstream to the battery or some broken strands. If that is the case, it can give you good voltage readings but not allow enough current to pass to engage the clutch.

I would keep the connector connected and do a voltage check of the wires at/near the connector to see if it drops way down while it is connected and/or the clutch tries to engage. You might have to pierce the insulation of the wires with a pin to make such a connection with your voltmeter. If the voltage drops way down, it indicates your wiring is not passing enough current to the clutch.