A/C clutch test help?

jpoke5

New member
I have read the forums about getting my ac unit tested and or fixed on my 03 2500. Some of the posts suggested you can test the clutch by hooking up a direct 12v line from the battery but unclear as to proper directions on how to get errrr done...

The dash light is on.... but the clutch does not kick in.

Also: Should I be able to turn the clutch by hand or with a strap of some sort to see if it's frozzzz up?


Thanks!!
Jeff
WI
 

sikwan

06 Tin Can
On the A/C clutch there should be a wire hanging off of it. Unplug it and connect 12V + to it. The clutch should engage.
 

mean_in_green

>2,000,000m in MB vans
So your dash is on, but the compressor isn't running? The 12v to compressor test seeks to establish if you can temporarily bypass the heater control panel and the wiring between it and the compressor. Look for the 12v feed on the compressor with a meter then place your feed there and see if the compressor starts or not.

I had the same symptoms on mine and found the cause lay in the heater control panel, but that's not to say it couldn't have been somewhere else either (i.e. the control wire to the compressor). When I jumped 12v to the compressor it started turning.
 

jpoke5

New member
Thanks for the help. I guess I will have to do the test soon... So if the compressor comes on I will assume the heater control panel is shot. does the entire unit need to be replaced or just one of the controls? is it hard to do yourself or do I require the dealer?

sure wish I had a picture of the back of that unit.

Jeff
 

abittenbinder

Doktor A (864-623-9110)
Testing the compressor clutch with a 12V jumper wire from battery + post to the center pin in the SOCKET on the compressor (not the wire you have disconnected for access to socket) will only establish if the clutch is operational.

It will not help you determine if you have sufficient refrigerant to allow activation of the clutch.

Doktor A
 

jpoke5

New member
Thanks Doctor A
so how do you suggest I proceed? get the refrigerant system tested and refilled to see then if the compressor/clutch will kick in?

Thanks
Jeff
 

mean_in_green

>2,000,000m in MB vans
... So if the compressor comes on I will assume the heater control panel is shot. does the entire unit need to be replaced or just one of the controls?
Not necessarily. If the compressor runs it suggests a power or refrigerant level issue. Although my power issue was the control panel it could just as easily have been somewhere in the wire between the panel and the compressor. The heater panel isn't difficult to remove but check your refrigerant first.
 

abittenbinder

Doktor A (864-623-9110)
Thanks Doctor A
so how do you suggest I proceed? get the refrigerant system tested and refilled to see then if the compressor/clutch will kick in?

Thanks
Jeff
By all means, test the clutch but access to the male center contact in the compressor's socket is somewhat difficult.

If clutch is operational, then have someone check refrigerant pressures with a manifold gauge or a diagnostic tool which can access the ATC module.

Doktor A
 

tymbo

New member
My clutch wasn't engaging. I gambled on a cheap fix, assuming coolant pressure was low. Spent $50 on 2 cans of R134a and guage/ hose. Good as new!
Tim:thumbup:
 

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