a/c clutch rapidly clicks on and off

[maximus7001]

Greetings.

A few weeks ago I was driving around in hot 30c weather and when I went to park at the supermarket I could hear lots of clicks coming from under the hood. Opened the hood and it was the a/c clutch clicking on and off at 1 second intervals, sometimes .5 of a second up to 2 seconds. Turned off the a/c and back on again and the problem went away until today.

Today I get in the Eagle to head to my new job, first day. Temp outside was 30c again. Started it up and turned on the a/c. Great, the clicking is back and will not go away. The a/c does still blow really cold but the engagement/disengagement thing is going to kill the clutch very soon so I only used the a/c in short bursts to keep from sweating buckets.

Later in the evening when cooler outside the a/c worked better. It would work fine for maybe 4-5 minutes of cycling on/off properly before the clicking comes back.


It is not the wires from the compressor or the pressure switch as I checked these out and jumpered the switch with no change.

Any ideas?

[Jurjen]

Could be the pressure switch near the radiator on drivers side.
It is a safety switch for the system pressure.
You can put a jumper on it for testing.
If that doesn't help, it could be the A/C thermostat.

[txjeeptx]

Probably the pressure switch doing what its supposed to do - its located on the driver side near where the radiator meets the grill support, inline with one of the AC lines. It is probably working properly, indicating insufficient pressure to operate the system - indicating a possible low refrigerant charge condition. Too little refrigerant, and the system works really well at cooling(in fact, it'll ice up), but there's less pressure than the system was designed for, and it indicates that someone with some in-depth knowledge and specialized tools needs to have a look at the system. I'd recommend taking it to a shop that specializes in AC repair for a diagnosis and likely recharging of the refrigerant, if no leaks are found.

[mudkicker715]

If it is low there would be bubbles in the sight glass. When its full its a constant stream.

[maximus7001]

Greetings.

A few weeks ago I was driving around in hot 30c weather and when I went to park at the supermarket I could hear lots of clicks coming from under the hood. Opened the hood and it was the a/c clutch clicking on and off at 1 second intervals, sometimes .5 of a second up to 2 seconds. Turned off the a/c and back on again and the problem went away until today.

Today I get in the Eagle to head to my new job, first day. Temp outside was 30c again. Started it up and turned on the a/c. Great, the clicking is back and will not go away. The a/c does still blow really cold but the engagement/disengagement thing is going to kill the clutch very soon so I only used the a/c in short bursts to keep from sweating buckets.

Later in the evening when cooler outside the a/c worked better. It would work fine for maybe 4-5 minutes of cycling on/off properly before the clicking comes back.


It is not the wires from the compressor or the pressure switch as I checked these out and jumpered the switch with no change.

Any ideas?

"It is not the wires from the compressor or the pressure switch as I checked these out and jumpered the switch with no change."

These things were the first to be checked.

[txjeeptx]

Microswitch in the control head in the dash may have a weak connection or poor contacts inside of it.

[Jurjen]

OK, we will get there. Check the micro switch as txjeeptx suggests.
The A/C thermostat is behind the glove compartment, you can put a jumper in those wires too for testing.

[maximus7001]

I have this little brass hammer and took it to the pressure switch and tapped it a whole bunch. Seems to work after doing that but for how long who knows. I will have to take the pressure switch out of the 81 Concord and swap it in. I can just dump the system since it if charged with redtek.

I can hear the thermostat behind the glove box clicking normally when it cycles the clutch on and off and it seems to work good now.

[Jurjen]

If so, then it should stop cycling too, when you put a jumper over the pressure switch (keeps cycling over the A/C thermostat though).
Did you observe any bubbles through the sight glass, your system pressure may be on the low side.

[maximus7001]

The glass is to foggy to see anything through. When I charged this system may 2010 I could not get any real readings from the gauge so I went by volume instead and it blows real cold. So after I put the other pressure switch in there then I will fill it up with 2 cans of redtek and it should be good to go and only cost $20. I will also change the plug that goes on the switch since it is not in the best condition.

[maximus7001]

Update.

I ended up dumping the system and refilling it again with 2 cans of redtek ($20) and the problem was still there. So I just jumpered the plug that goes to the pressure switch and it has worked great ever since. I saw no need to replace the pressure switch since I know the system is full and does not leak. For the winter months I will just remove the jumper and of course leave it unplugged.