AC/Heat control - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Sheenanny · 05-21-2002, 07:50 AM

Has anybody had much experience working on the inside controls for a/c etc.? First the levers started sticking together and the heat wouldn't come out of the floor or the dash registers, then the blower motor quit working. I put a new fuse in the a/c slot and as soon as you turn the ignition on, the fuse blows. I know i've got a short somewhere, but how can I find it??

JimKshortstep4x4 · 05-21-2002, 08:59 AM

From what you are describing my guess is that the blower motor is bad or it is clogged with leaves and can't turn. Also,
it sounds like your diverter box door is not working, (common problem).

These are the items that I would look at first,

Jim

barn9 · 05-21-2002, 09:13 AM

I agree with Jim, but also check the wires. I had a similar problem, and it turned out to be a wire that had gotten hot and melted the cover, which was allowing it to short out. A good cleaning and lube of the control arms can never hurt while you have things apart. Good luck.

------------------[*]'71 Cheyenne, 402BB[*]Winfield, KS[*] http://barn9.freeservers.com

Sheenanny · 05-21-2002, 10:20 AM

I checked the two flapper boxes on the inside and got them to open and close. Now the top lever (outside air, inside air, defrost) is only one not doing anything. Which diverter box does this control?

JimKshortstep4x4 · 05-22-2002, 06:45 AM

The top lever moves the door in the diverter
box. This is the box with the "s" connector
connected to it. Usually the door in the diverter box does not move with the shaft
because the door breaks at the interface with the shaft, (steel shaft, plastic door).

The diverter box is not too hard to remove
and you will want to check it. The door to shaft can be repaired. We rivet in a small
sheet metal plate and weld the plate to the shaft. Some of the guys have used epoxie for the repair.

Jim

Sheenanny · 05-22-2002, 08:45 AM

For the blower motor:
I hotwired the motor last night and it ran fine. Then I unplugged the fan switch and put another fuse in the socket. Turn on the ignition and the fuse does not blow. Guess this narrows it down to the switch right?

I'll dig into the duct work this weekend.

Thanks for your help so far. I just recently bought this truck and I really love driving it.

05-21-2002, 07:50 AM	#1
Sheenanny Registered User Join Date: May 2002 Location: Lexington, KY Posts: 23	AC/Heat control Has anybody had much experience working on the inside controls for a/c etc.? First the levers started sticking together and the heat wouldn't come out of the floor or the dash registers, then the blower motor quit working. I put a new fuse in the a/c slot and as soon as you turn the ignition on, the fuse blows. I know i've got a short somewhere, but how can I find it??

05-21-2002, 08:59 AM	#2
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	From what you are describing my guess is that the blower motor is bad or it is clogged with leaves and can't turn. Also, it sounds like your diverter box door is not working, (common problem). These are the items that I would look at first, Jim __________________ 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

05-21-2002, 09:13 AM	#3
barn9 Half a bubble off! Join Date: Jun 2000 Location: Winfield, Ks, USA Posts: 5,588	I agree with Jim, but also check the wires. I had a similar problem, and it turned out to be a wire that had gotten hot and melted the cover, which was allowing it to short out. A good cleaning and lube of the control arms can never hurt while you have things apart. Good luck. ------------------[]'71 Cheyenne, 402BB[]Winfield, KS[*] http://barn9.freeservers.com __________________ Just call me LB. '71 Cheyenne, 402BB, hauls blondes, brunettes, or redheads.

05-22-2002, 06:45 AM	#5
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	The top lever moves the door in the diverter box. This is the box with the "s" connector connected to it. Usually the door in the diverter box does not move with the shaft because the door breaks at the interface with the shaft, (steel shaft, plastic door). The diverter box is not too hard to remove and you will want to check it. The door to shaft can be repaired. We rivet in a small sheet metal plate and weld the plate to the shaft. Some of the guys have used epoxie for the repair. Jim __________________ 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

05-21-2002, 10:20 AM	#4
Sheenanny Registered User Join Date: May 2002 Location: Lexington, KY Posts: 23	I checked the two flapper boxes on the inside and got them to open and close. Now the top lever (outside air, inside air, defrost) is only one not doing anything. Which diverter box does this control?

05-22-2002, 08:45 AM	#6
Sheenanny Registered User Join Date: May 2002 Location: Lexington, KY Posts: 23	For the blower motor: I hotwired the motor last night and it ran fine. Then I unplugged the fan switch and put another fuse in the socket. Turn on the ignition and the fuse does not blow. Guess this narrows it down to the switch right? I'll dig into the duct work this weekend. Thanks for your help so far. I just recently bought this truck and I really love driving it.



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