A/C compressor stopped working.

[speleopower]

My AC compressor stopped working yesterday. I have a feeling it's related to the magnetic field generator. I'm making a guess on the magnetic field generator because the A/C worked fine the day before. I don't hear the A/C clutch engaging or disengaging.

Does anyone have any troubleshooting advice regarding the A/C compressor magnetic field generator? Or know of any common wiring issues that I might encounter.

I did replace the A/C clutch last year. That's why I'm leaning toward the field generator. I'm not sure I put any dielectric grease on the connector....

Thanks-Scott

 

[BrooklynBay]

Check the low pressure cut out switch, and the freon pressure in the system. As for the clutch coil, you could use a multimeter set in the Ohm range to check the resistance. Check the relay as well.

 

[speleopower]

I am pointing my finger at the coil. But my next suspicion is a vacuum control line. I may have busted one when I was under the hood the other day.

I had a similar issue a couple years ago where the AC would come on and off and it was a leaky vacuum line. But I seem to remember the clutch would engage and disengage when the line was popped.

-Scott

 

[BrooklynBay]

Check the electrical parts first.

 

[speleopower]

I checked a lot of things today but none of them got power to the A/C compressor.
I first checked voltage on the compressor plug with the A/C set to Max. No voltage.
Second I checked for voltage at the selector switch on the dash. There was voltage here!
Third I checked out the relays and replaced 2. But not sure which relays are which. I could only find 3 relays. They were just behind the battery on the side wall. The little relay housing had 3 relays and one diode. The diode was ok.
The relays appear ok. I also replaced the 2 similar relays in the box. 2 were the same and the one between was different.
Fourth I checked what I think is the low pressure switch and it seems ok.
5th checked low side pressure with my A/C pressure checker. It had plenty of pressure.

My biggest question is did I check the correct relays? Where is the A/C compressor relay located at?

Im not sure where to go next in looking for the issue. Any ideas????

Thanks-Scott

 

[BrooklynBay]

There are a few relays in a row. One of them is the A/C relay. Do you have a manual such as Haynes or Chilton? Use a test light inside of the socket for the A/C relay to check for voltage when the A/C is turned on. If there is no voltage in the socket, then it could be a wiring malfunction since you said that the switch & low pressure cut out switch have voltage.

 

[speleopower]

I do have the basic Hayes manual.
I have not tested the sockets of the relay as I don't know how to test the actual socket.
I did check the relays and they appeared to function ok.
Today my goal is to learn how to check the relay sockets. Any tips?

I'm thinking if I cant get the A/C compressor some voltage via the stock system I'm gonna wire up a dash board switch to manually turn the compressor on and off..... It's getting near summer time and I'm not gonna be able to go without AC for much longer.

-Scott

 

[BrooklynBay]

Checking the relay socket is simple. You have 2 wires for power going to the coil, and another 2 wires for the relay contacts. Check the coil connections for power when the system is on. Shorting the relay contacts (not the coil contacts) will activate the compressor clutch.

 

[speleopower]

All three relay sockets have power. All three relays seem to function i.e. they test with almost no resistance across the coil and infinate resistance across the switch side.

Now here's the kicker. When I put my fingers on each relay I feel and hear them clicking when a friend turns on the ignition with the dashboard AC switch set to on. I can also see and hear the compressor clutch snap closed but it comes undone a split second later when the ignition is turned on with the dash ac switch set to max.

Any ideas?

 

[BrooklynBay]

Substitute a test light in place of the A/C clutch, and repeat the test. If the same results occur, repeat this test with a jumper wire in the place where the low pressure cut out switch is connected.

 

[speleopower]

I'm getting this narrowed down. I did get the 1997 Aerostar factory vacum and electrical troubleshooting manual.

I have a feeling there is something with the temperature sensing equipment. I found the WOT Relay circuit is not functioning correctly. My work around on this issue it to keep the WOT Relay from closing and turning off the A/C clutch magnetic field generator.

Now I have to figure out why the PCM is giving a signal to energize the WOT relay.

At this point I have A/C but something is still not correct.

My next question is what's going on with my temperature gauge?? This relates I think back to my first question on the forum about overheating.....

-Scott

 

[BrooklynBay]

The temperature sending unit is connected to the temperature gauge in the vheicle. The engine coolant temperature sensor is for the computer, and nothing else senses temperature (except for the internal temperature sensor in the transmission's wiring harness).

 

[speleopower]

I saw the circuit diagrams showing the temp sensor.
I did replace the temperature sensor that is next to the thermostat a couple weeks ago because my temperature gauge was showing the van was overheating. I used a couple different temperature guns to check the temps of various components and the results showed everything was cool. As in the thermostat housing was about 180 degrees and other components were cool as well. I'm was guessing the temp sensor was faulty and I replaced it. Nothing changed and the temp gauge was still showing the van as running very very hot.
For years the temp gauge at normal operating range was with the needle between the O and R on the gauge. If the van was starting to over heat it would be between the R and the M. Now the normal operating range of the gauge has the needle between the M and A. Not sure why this is.

 

[BrooklynBay]

Did you replace the thermostat or the fan clutch? It's possible that the gauge might be defective or the sensor might be out of spec even though it's new. Are the fan shroud, and fan blades in good condition?

 

[speleopower]

I'm not sure which I replaced now. I unscrewed the sensor from next to the thermostat housing and replaced that sensor. I see there is 2 engine coolant temperature sensors listed on the drawing in my book. but it's not clear which is which and where they are located exactly.
-Scott

 

[BrooklynBay]

Unplug one of them, and see if your temperature gauge cuts out.

 

[speleopower]

I replaced the temp gauge sensor last night. Hopefully it will work now. Gonna try and drive the van tonight after work.

 

[speleopower]

Here's where I'm at so far. I drove the van on highway for about an hour. The temp gauge was nearly pegged on hot the entire time. When I got home I used my infrared temp gun to check temps. The upper radiator hose was a little over 200.
It sounded like a lot of coolant was going from the radiator into the overflow reservoir. This morning I checked the coolant level in the radiator and it was nearly at the top so all good there.
I've replaced the temp guage sensor and the coolant temp sensor.
At this point I"m not sure where to go next. Maybe just replace the radiator since there might be a blockage in it somewhere and while I'm at it replace the water pump just for good measure.
I'm convinced the van is running much hotter than it has at anytime in the past which is why my a/c compressor WOT/overheat relay is being tripped.

Any ideas????

Thanks-Scott

 

[BrooklynBay]

Check the fan clutch as previously suggested. A bad fan clutch would prevent the fan from turning at the correct speed. The radiator could be flushed instead of being replaced. Prestone sells heavy duty cooling system cleaner.

 

[speleopower]

I replaced the radiator and it seems to have cured all of my problems.!