67 air conditioner problems - The 1947 - Present Chevrolet & GMC Truck Message Board Network

easyrider · 03-20-2010, 08:07 PM

I am having problems with my a/c. The clutch isn't engaging when I turn on a/c fan. I know on the 67 you have to put the lever on a/c and on cold and then turn on the fan to make it come on. The fan comes on. With all that done, clutch still doesn't engage. I made sure the fuse was good and that the plug on the compressor was plugged in good. I have a relay in the circuit and there is the fan switch itself. Any suggestions as to where to start the tracing process? What is the most likely thing to go wrong. I had the a/c serviced last summer and the truck has set in the shop all winter. Yesterday was the first time that I tried to use the a/c and found that it didn't work. Any suggestions would be appreciated. Thanks

Shyguy · 03-20-2010, 08:11 PM

It sounds like it is low on charge.

Mine did the same thing and I charged more freon in it and it now works.

Danny

caja_larga · 03-20-2010, 10:42 PM

I would guess low charge.

hayhauler71 · 03-20-2010, 11:21 PM

Do you have power to the ac clutch. Does the clutch engage.

easyrider · 03-21-2010, 12:01 AM

I haven't jumped the clutch power to see if it will engage or if it is something else besides a power issue.

JimKshortstep4x4 · 03-21-2010, 09:31 AM

Unless it has been added there is not a low pressure switch on the compressor. I would suggest using a jumper wire to the compressor, (positive side) to see if the clutch will pull in, engine off).

Here is a diagram of the wiring on the AC. (I have not seen trucks with the anti-dieseling relay so yours probably does not have one).

03-20-2010, 08:07 PM	#1
easyrider Registered User Join Date: Jan 2009 Location: Stanley, N.C. Posts: 161	67 air conditioner problems I am having problems with my a/c. The clutch isn't engaging when I turn on a/c fan. I know on the 67 you have to put the lever on a/c and on cold and then turn on the fan to make it come on. The fan comes on. With all that done, clutch still doesn't engage. I made sure the fuse was good and that the plug on the compressor was plugged in good. I have a relay in the circuit and there is the fan switch itself. Any suggestions as to where to start the tracing process? What is the most likely thing to go wrong. I had the a/c serviced last summer and the truck has set in the shop all winter. Yesterday was the first time that I tried to use the a/c and found that it didn't work. Any suggestions would be appreciated. Thanks

03-20-2010, 08:11 PM	#2
Shyguy Junior Member Join Date: Dec 2006 Location: Southeast Missouri Posts: 2,436	Re: 67 air conditioner problems It sounds like it is low on charge. Mine did the same thing and I charged more freon in it and it now works. Danny __________________ '67 Chevy C-20 short stepper - build complete, 454/SM-465. '75 C-30 Single Cab DRW-350 small block/NP-435. '77 GMC-6500 Dump Truck, 427 Tall Deck. '92 GMC K-3500 Duallie, 454/4L80E.

03-20-2010, 10:42 PM	#3
caja_larga Registered User Join Date: Oct 2007 Location: Tucson, Az Posts: 172	Re: 67 air conditioner problems I would guess low charge.

03-20-2010, 11:21 PM	#4
hayhauler71 Registered User Join Date: Aug 2009 Location: St. Paul MN. Posts: 1,996	Re: 67 air conditioner problems Do you have power to the ac clutch. Does the clutch engage.

03-21-2010, 12:01 AM	#5
easyrider Registered User Join Date: Jan 2009 Location: Stanley, N.C. Posts: 161	Re: 67 air conditioner problems I haven't jumped the clutch power to see if it will engage or if it is something else besides a power issue.

03-21-2010, 09:31 AM	#6
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: 67 air conditioner problems Unless it has been added there is not a low pressure switch on the compressor. I would suggest using a jumper wire to the compressor, (positive side) to see if the clutch will pull in, engine off). Here is a diagram of the wiring on the AC. (I have not seen trucks with the anti-dieseling relay so yours probably does not have one). Attached Images __________________ 1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC Last edited by JimKshortstep4x4; 03-21-2010 at 09:33 AM. Reason: wording

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