Fan how hard should it blow? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

WHYBYNU · 07-10-2002, 12:18 PM

I was running my air conditioning today in my 71 Super and it just doesn't seem to blow very hard. Its a stock unit and the air is very cold. If you put the fan switch on high ( all the way down ) it won't blow at all. I run the air more just to run it than I do
because of heat ( Ontario,NY doesn't get that hot ) Just wondering if this normal or is the fan switch bad? I know it is'nt going to freeze me out of the truck but I would like it to blow alittle harder. I had a 69 short step w/a 250 straight 6 in it, my father bought new in 69 and it had factory air it was the only straight 6 I've ever seen with factory air it had 3 on the tree no power steering or brakes just air. Sorry to ramble just a slow day at work.

Old Dave · 07-10-2002, 01:17 PM

Sounds like your high speed fan relay isn't working. It's located on the ac housing below and behind the glove box. Put the fan switch on high and take a screwdriver handle and tap on the relay. If it runs, then the contacts on the relay are burned and you'll need to replace it. These are available at most auto parts stores. Hope this helps.

jku72 · 07-10-2002, 01:26 PM

good idea, another possibility is the switch itself, in my expirience, the switch in the dash lasts about 2 seasons.

WHYBYNU · 07-10-2002, 01:52 PM

Thanks guys I'll check both of them out and let you know what I find.

Project1970 · 07-10-2002, 06:05 PM

Mine's been eating switches every few months lately, and the wiring gets too hot for comfort on high so I have that disconnected...but I'm gonna buy a new blower motor soon and see if that helps. The one in there is a 10 year old crap rebuilt one...

jhow66 · 07-10-2002, 07:50 PM

Check the large red wire at fuse panel. It plugs in to a socket labled ing. This wire supplies current to the relay on AC box beside glove box. With switch on you should have current to relay at the red wire. (with blower switch on high it closes a set of contacts sending 12 volts to fan motor).If no current at relay trace wire back to fuse panel. You probley will find a loose connection somewhere that has gotten hot enough to make a bad connection. ( Fixed a 71 this past week that had the exact problem you have--it had the above problem). Hope this helps.

jhow66 · 07-10-2002, 07:54 PM

Sorry forgot to tell you how to check fan speed--disconnect wire at fan motor and run a jumber from battery hot post to fan--this is how fast it should run on high.

07-10-2002, 12:18 PM	#1
WHYBYNU WHYBYNU when old will do Join Date: Feb 2002 Location: Hot Springs, AR. Posts: 643	Fan how hard should it blow? I was running my air conditioning today in my 71 Super and it just doesn't seem to blow very hard. Its a stock unit and the air is very cold. If you put the fan switch on high ( all the way down ) it won't blow at all. I run the air more just to run it than I do because of heat ( Ontario,NY doesn't get that hot ) Just wondering if this normal or is the fan switch bad? I know it is'nt going to freeze me out of the truck but I would like it to blow alittle harder. I had a 69 short step w/a 250 straight 6 in it, my father bought new in 69 and it had factory air it was the only straight 6 I've ever seen with factory air it had 3 on the tree no power steering or brakes just air. Sorry to ramble just a slow day at work.

07-10-2002, 01:26 PM	#3
jku72 Registered User Join Date: Jan 2002 Location: cornville, maine Posts: 659	good idea, another possibility is the switch itself, in my expirience, the switch in the dash lasts about 2 seasons. __________________ jku Cornville, Maine 68 C10 burb 42 Willys MB 46 Dodge WF-32 1.5 ton 53 & 56 Olds' 60 Cadillac 22 Dodge Brothers

07-10-2002, 01:52 PM	#4
WHYBYNU WHYBYNU when old will do Join Date: Feb 2002 Location: Hot Springs, AR. Posts: 643	Thanks guys I'll check both of them out and let you know what I find. __________________ 71 Cheyenne super 2 tone green and white ZZ6 - Th350 4/6 drop 20x8.5 / 20x10 Billet Specialties

07-10-2002, 06:05 PM	#5
Project1970 14.1 @ 96MPH Join Date: Jul 2001 Location: Mesa, AZ Posts: 2,811	Mine's been eating switches every few months lately, and the wiring gets too hot for comfort on high so I have that disconnected...but I'm gonna buy a new blower motor soon and see if that helps. The one in there is a 10 year old crap rebuilt one... __________________ Project1970 - LS1 Swap Complete!

07-10-2002, 07:50 PM	#6
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	Fan Check the large red wire at fuse panel. It plugs in to a socket labled ing. This wire supplies current to the relay on AC box beside glove box. With switch on you should have current to relay at the red wire. (with blower switch on high it closes a set of contacts sending 12 volts to fan motor).If no current at relay trace wire back to fuse panel. You probley will find a loose connection somewhere that has gotten hot enough to make a bad connection. ( Fixed a 71 this past week that had the exact problem you have--it had the above problem). Hope this helps. Attached Images __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

07-10-2002, 01:17 PM	#2
Old Dave Is a bullfrog waterproof? Join Date: Nov 2000 Location: OLATHE, KANSAS Posts: 1,130	Sounds like your high speed fan relay isn't working. It's located on the ac housing below and behind the glove box. Put the fan switch on high and take a screwdriver handle and tap on the relay. If it runs, then the contacts on the relay are burned and you'll need to replace it. These are available at most auto parts stores. Hope this helps.

07-10-2002, 07:54 PM	#7
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	fan Sorry forgot to tell you how to check fan speed--disconnect wire at fan motor and run a jumber from battery hot post to fan--this is how fast it should run on high. __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer



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