06-15-2007, 12:23 PM | #1 |
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Join Date: Mar 2006
Location: Gilbert, AZ
Posts: 179
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72 A/c
So I got the top on the '72 this week and drove it around for the first time this summer (had the top off for painting and freshening up). BTW, summer here in AZ is hot in case you didn't know. Up until last night the air was working fine, but last night with the blower on high, it cut out on me. I can still turn it on the low setting, but when I switch it all the way down to hi, it doesn't blow. Where should I start? Do you think it's the switch? Or the blower motor? I hate to start throwing parts at it, any suggestions for trouble shooting are appreciated. Thanks.
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06-15-2007, 01:15 PM | #2 |
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Join Date: Jul 2001
Location: North Louisiana
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Re: 72 A/c
I would start by checking the wiring at the blower switch. It is a notorious problem area. If you don't find a bad connection, or burnt wire, check the blower switch. If it blows on low, then your blower motor is good. Here is a FAQ link to a schematic, and some other good info. http://67-72chevytrucks.com/vboard/s...d.php?t=216549
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06-15-2007, 01:47 PM | #3 |
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Join Date: Sep 2001
Location: Bothell, WA
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Re: 72 A/c
You need to replace the highspeed blower relay. I have the same problem - the two lower settings work, but nothing in high. I have replaced the the switch (twice) and the resister. WES at Classicheartbeat.com informed me that it is the highspeed blower relay that causes this problem. I've got the new one sitting in the garage, just waiting to install it.
The highspeed blower relay is located under the glove box and is a pain to get at. Second item down on http://classicheartbeat.com/heater_&_a_c_2.htm
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06-17-2007, 06:38 PM | #4 |
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Join Date: Apr 2006
Location: Pendleton, OR
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Re: 72 A/c
Try checking the fuse. Mine would only work on two speeds until i replaced the 15 amp fuse for it. If it blows the fuse again. I would replace the relay.
The fuse is the second row down and third one over to the right.
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Mike T. Oregon 70 GMC Jimmy 4x4 70 Camaro LS1 plans in the works 71 RS/SS Camaro numbers matching 86 Chevy Silverado SWB 4x4 (454 merlin heads, 3/4 running gear upgrade, Detroit lockers front and rear) Last edited by EFI70Blazer; 06-17-2007 at 06:46 PM. |
06-18-2007, 05:49 PM | #5 |
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Join Date: Mar 2006
Location: Gilbert, AZ
Posts: 179
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Re: 72 A/c
Thanks for the feedback guys. As it turns out, this thing has turned into a larger project than I hoped for. I replaced the terminals on the back of the switch which seemed to fiix the blower. However, when I started it up, the compressor belt starting squeeling really bad. So I inspected the belt and it was loose, so I tightened it up and it squeeled worse. Not only that, but the water pump pulley started wobbling badly too, probably from a misalignment of the compressor (PO). So I inspected the water pump and it was about ready to go on me, the bearings seem shot inside. So what started as a simple fix, has turned into tearing the front of the motor appart trying to re-align pullies and new pumps, etc. Always something with these trucks. I'll keep you all posted.
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