A/C clutch cycling issue

[guyace]

I have a 93 ranger 2.3L with an a/c that has been shop retrofitted for R-134a. The compressor clutch does not engage when the blower is turned on unless I tap the clutch with a screwdriver the clutch will then suck in and run for a second or so and then turn off until I tap it again. I jumped the low pressure switch and the clutch did not turn on until I tapped and then it stayed on continuously until I turned the a/c off. I add R-134a to the system and the gauges now read a constant 20 on the low side and about 170 on the high side with it being about 90 degrees outside. When I am driving with the windows down, the a/c button pushed in but with the selector switch turned to off I can hear the clutch cycling every 5 to 10 seconds but as soon as I turn the selector switch on to start the blower the clutch stops cycling and just stays off.

I think that the low pressure switch is bad but what else is the issue as that does not seem to explain the clutch not sucking in when the blower is on?

 

[adsm08]

It sounds like the field coil is getting very weak.

 

[RonD]

The newer Ford A/C clutches would do this same thing, where a tap on the clutch would cause it to engage.

There is an air gap that has gotten to big and can be shimmed without losing refrigerant.

google: how to shim ford a/c clutch

You can usually test the field coil with an ohm meter, should be about 4 ohms...I think, 0ohms or very high ohms would be a bad coil
And test the wire/connector to make sure it isn't corroded, and has power all the time, i.e. not cycling

There are also A/C clutch cut out relays on most A/C systems, wide open throttle cut out for example, that would be controlled by the TPS and PCM, so when your foot is to the floor the A/C is shut off to give you full power, but if it is acting up.............can't see a tap on the clutch fix that though.

 

[shane96ranger]

Best way to tell is take the connector off and see if you are cycling voltage. I'd say Adsm is correct though.

Sent from the can

 

[guyace]

Thank you for the help so far.

I pulled the connector from the compressor and checked the voltage. After the truck had idled for a minute or so the voltage read at a steady 14.1. I also checked the ohms on the clutch while I had the connector off and it read a steady 4 ohms too. Once I hooked the connector back up the clutch would pull in a few times and then stop pulling in. If I tapped the clutch it would pull in and run for a few seconds and then stop again.

I think that I need to re-shim the clutch as the gap appears to be too wide.

 

[adsm08]

Got any feeler gauges? You can check the gap and make sure it is wrong before tearing it all apart. You need them to make sure it is right when repairing it anyway.

 

[guyace]

I just picked some up. The gap is .062". I'm going to have to wait for the engine to cool so I can pull the radiator hose off so I can pull the clutch face plate off to adjust the gap.

 

[adsm08]

Yup, that's about twice what it is supposed to be. Air gap spec is .018-.033"