Heat/defrost help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Thealien · 08-27-2009, 08:08 PM

I tried a few searches and couldn't find an answer.

My 72 Jimmy is an AC truck but the AC doesn't work but that is not the problem. Last time I had the truck out I could get heat out the defroster, the dash vents, and heat. Today coming back from a cruise all I can get is heat out the dash vents. How and what do I need to take apart to fix this? Can everything be done under the dash?

Thanks
Mark

JimKshortstep4x4 · 08-27-2009, 08:14 PM

Check the diverter box. It sounds like the door in it has broken away from the shaft that turns it. The box is under the dash.

Jim

cdowns · 08-27-2009, 08:26 PM

diverter box is the black box on the passenger side floor//very common for the flapper inside to fail

Thealien · 08-27-2009, 08:58 PM

If the flapper is broken how hard are they to find?

Anything I should know about getting to it (hidden bolts?)

JimKshortstep4x4 · 08-28-2009, 07:49 AM

It is easier to see and work on the diverter box if you remove the glove box door and glove box. In the picture the diverter box is the part that is hanging by the cable. It is pretty straight forward to change out the box if the door is bad. The boxes are available new.

Jim

Thealien · 08-28-2009, 07:52 AM

Thank you, that is exactly the kind of info I was looking for!!

Hottrucks · 08-28-2009, 10:00 AM

as long as you guy are talking heat my truck with AC the heater temp door doesn't seem to open all the way ??? If I go under the hood and unhook the cable the door doesn't feel like its going all the way open?? my guess is there is some sort of mice parts in there what is the easy ( lol ) way to get in there ??? do I have to pull the box from the engine compart ment??? or can I get in there from inside?? I'm hoping to stick a vac in there??

Thealien · 09-05-2009, 01:20 PM

Just a bump so maybe hottrucks will get an answer and to say my epoxy repair seems to be holding well. I did find a GM one on ebay and put it on the shelf, just in case!

Hottrucks · 09-05-2009, 03:34 PM

in answer to Hottrucks post you can pull half of the A/C box off remove the condencer and get to most of it...with a little help from a piece of wire you can get ther est loose and then turn on the blower to high it will blow all the junk out clean the rubber seal area up and your good as gold.....takes about an hour or so.....

Oh wait!!! I am Hottrucks...ok I confess I did it yesterday..also found that the heat defrost door was broken off but that is an inside the cab job...

08-27-2009, 08:08 PM	#1
Thealien Senior Member Join Date: Jun 2007 Location: Pine Ridge Florida Posts: 4,125	Heat/defrost help I tried a few searches and couldn't find an answer. My 72 Jimmy is an AC truck but the AC doesn't work but that is not the problem. Last time I had the truck out I could get heat out the defroster, the dash vents, and heat. Today coming back from a cruise all I can get is heat out the dash vents. How and what do I need to take apart to fix this? Can everything be done under the dash? Thanks Mark

08-27-2009, 08:14 PM	#2
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: Heat/defrost help Check the diverter box. It sounds like the door in it has broken away from the shaft that turns it. The box is under the dash. 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

08-27-2009, 08:26 PM	#3
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: Heat/defrost help diverter box is the black box on the passenger side floor//very common for the flapper inside to fail __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

08-27-2009, 08:58 PM	#4
Thealien Senior Member Join Date: Jun 2007 Location: Pine Ridge Florida Posts: 4,125	Re: Heat/defrost help If the flapper is broken how hard are they to find? Anything I should know about getting to it (hidden bolts?)

08-28-2009, 07:49 AM	#5
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: Heat/defrost help It is easier to see and work on the diverter box if you remove the glove box door and glove box. In the picture the diverter box is the part that is hanging by the cable. It is pretty straight forward to change out the box if the door is bad. The boxes are available new. Jim 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

08-28-2009, 07:52 AM	#6
Thealien Senior Member Join Date: Jun 2007 Location: Pine Ridge Florida Posts: 4,125	Re: Heat/defrost help Thank you, that is exactly the kind of info I was looking for!!

08-28-2009, 10:00 AM	#7
Hottrucks Redefining LowBudget Join Date: Mar 2009 Location: lebanon Cow Hampshire Posts: 4,538	Re: Heat/defrost help as long as you guy are talking heat my truck with AC the heater temp door doesn't seem to open all the way ??? If I go under the hood and unhook the cable the door doesn't feel like its going all the way open?? my guess is there is some sort of mice parts in there what is the easy ( lol ) way to get in there ??? do I have to pull the box from the engine compart ment??? or can I get in there from inside?? I'm hoping to stick a vac in there??

09-05-2009, 01:20 PM	#8
Thealien Senior Member Join Date: Jun 2007 Location: Pine Ridge Florida Posts: 4,125	Re: Heat/defrost help Just a bump so maybe hottrucks will get an answer and to say my epoxy repair seems to be holding well. I did find a GM one on ebay and put it on the shelf, just in case!

09-05-2009, 03:34 PM	#9
Hottrucks Redefining LowBudget Join Date: Mar 2009 Location: lebanon Cow Hampshire Posts: 4,538	Re: Heat/defrost help in answer to Hottrucks post you can pull half of the A/C box off remove the condencer and get to most of it...with a little help from a piece of wire you can get ther est loose and then turn on the blower to high it will blow all the junk out clean the rubber seal area up and your good as gold.....takes about an hour or so..... Oh wait!!! I am Hottrucks...ok I confess I did it yesterday..also found that the heat defrost door was broken off but that is an inside the cab job...



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.