Changing heatrer core on an A/C truck? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Rdub · 10-10-2005, 05:19 PM

There's a great write up, with pics, in the FAQ section about changing the heater core on a non AC truck.... Anyone here ever chaged a heater core on an AC truck? Any different process than what is indicated in the FAQ? At one time I'm pretty sure there was a thread on here about it but, can't find it. I've been putting this off and need to get it done (71 GMC 4x4)..... any help would be appreciated.... thanks!

Hutch · 10-10-2005, 08:36 PM

Rdub
I don't have the link but it is pretty basic stuff.
The unusual stuff that seems to come to mind is:
You will need to remove the passenger side hood hinge, also the inner passenger fender.
This is because there is one nut on the case (at the bottom) that you cannot get a wrench on due to clearance issues.
I got a kit and replaced all the seals at the same time, there is also a drain tube (not part of the kit which I did not think that I would need at first but later I am glad I did replace it.
If you are ordering parts go ahead and get the cowl vent repair rubber seals, easy fix and helps allot.
Remember that the heater hoses upper and lower are different sizes.

kaycee · 10-11-2005, 12:20 AM

I just changed mine last week start from the center and work your way to the pass. side,your heater floor vent will seperate from the S-duct and it will seperate from the air selector duct.I was able to keep all my wires and cables in tact and push them out of the way.You will need to take your glove box liner out allso.When all the heater boxes and liner are removed you should be able to pull your carpet back and find 4 (I BELIVE) bolts to unscrew around the heater core box then go drain rad. and remove heater hose's.You should be able to remove the heater core housing and unplug the A/C relay this should get you free to remove the core itself.There are 4 little tiny screws that hold a bracket to hold the core in place they are a PITA to put back together.It took me about 2 hrs to do HOPE THIS MAKES SENCE

73stepside · 10-11-2005, 12:28 AM

it will go somewhat easier if you take out the passenger side hood hinge. it's more invovled than a noa/c truck but just as easy

mrein3 · 10-11-2005, 09:53 AM

It could be worse. You could have to replace the heater core on your daily driver. In my case a '94 Ford Escort.
I believe Ford put the core in the heater box, and started the assembly line with that assembly. I had to remove the whole dash board to get to it.

The motor manual gives 4 hours for the job. Surfing the internet I read where backyarders were taking 12-14 hours. I finished in 7 hours counting beer brakes and a one hour ice cream/time for bed break with my 3 year old.

The heater core in an AC truck is a snap compared to the Escort. I believe if you have the right swivel and small enough hands you can get by with leaving the hood hinge in place. Some people punch a hole in the inner fender when then can't reach the lower right nut holding the heater box in place.

I attached three photos. The first is what you are looking for sticking out of the firewall of your truck. These bolt like deals are clipped on to the heater box on the inside. They stick out of the firewall.

The next two are for if anybody is curious what an Escort looks like without a dash. I just had to take a picture of my gutted car. And the pile of plastic I made while doing it.

Rdub · 10-11-2005, 09:54 AM

Kaycee..... thanks that's great informantion. If I understand you correctly, on my AC truck, the heater core comes out from inside the cab as opposed to from under the hood. This would mean I don't need to remove the hood hinge and fender liner as written up in the FAQ but do need to remove the glove box, ducts, wiring and cables as you indicate.

10-10-2005, 05:19 PM	#1
Rdub Registered User Join Date: Feb 2005 Location: Portland OR Posts: 74	Changing heatrer core on an A/C truck? There's a great write up, with pics, in the FAQ section about changing the heater core on a non AC truck.... Anyone here ever chaged a heater core on an AC truck? Any different process than what is indicated in the FAQ? At one time I'm pretty sure there was a thread on here about it but, can't find it. I've been putting this off and need to get it done (71 GMC 4x4)..... any help would be appreciated.... thanks!

10-10-2005, 08:36 PM	#2
Hutch Registered User Join Date: Oct 2001 Location: Grapevine, Tx. Posts: 2,140	Rdub I don't have the link but it is pretty basic stuff. The unusual stuff that seems to come to mind is: You will need to remove the passenger side hood hinge, also the inner passenger fender. This is because there is one nut on the case (at the bottom) that you cannot get a wrench on due to clearance issues. I got a kit and replaced all the seals at the same time, there is also a drain tube (not part of the kit which I did not think that I would need at first but later I am glad I did replace it. If you are ordering parts go ahead and get the cowl vent repair rubber seals, easy fix and helps allot. Remember that the heater hoses upper and lower are different sizes. __________________ John Hutchison Grapevine,Texas 68 1/2 t swb 68 Mustang 69 Jaguar 71 1/2 t swb 88 Supra CompTs6m 93 Escort GT 2005 Corolla XRS

10-11-2005, 12:20 AM	#3
kaycee Registered User Join Date: Jan 2000 Location: Wyoming USA Posts: 2,445	I just changed mine last week start from the center and work your way to the pass. side,your heater floor vent will seperate from the S-duct and it will seperate from the air selector duct.I was able to keep all my wires and cables in tact and push them out of the way.You will need to take your glove box liner out allso.When all the heater boxes and liner are removed you should be able to pull your carpet back and find 4 (I BELIVE) bolts to unscrew around the heater core box then go drain rad. and remove heater hose's.You should be able to remove the heater core housing and unplug the A/C relay this should get you free to remove the core itself.There are 4 little tiny screws that hold a bracket to hold the core in place they are a PITA to put back together.It took me about 2 hrs to do HOPE THIS MAKES SENCE __________________ 2001 Silverado K-1500 2005 FXDWG stage3 69 CHEVY Short/Step 327/4L60 373 posi 63 IMPALA 327

10-11-2005, 12:28 AM	#4
73stepside Registered User Join Date: Feb 2002 Location: Moore OK 73160 Posts: 974	it will go somewhat easier if you take out the passenger side hood hinge. it's more invovled than a noa/c truck but just as easy __________________ 04 GMC Sierra RCSS 70 CST LWB 04 HD Sportster 1200 Custom

10-11-2005, 09:53 AM	#5
mrein3 Registered User Join Date: Feb 2000 Location: Center City, MN, USA Posts: 3,253	It could be worse. You could have to replace the heater core on your daily driver. In my case a '94 Ford Escort. I believe Ford put the core in the heater box, and started the assembly line with that assembly. I had to remove the whole dash board to get to it. The motor manual gives 4 hours for the job. Surfing the internet I read where backyarders were taking 12-14 hours. I finished in 7 hours counting beer brakes and a one hour ice cream/time for bed break with my 3 year old. The heater core in an AC truck is a snap compared to the Escort. I believe if you have the right swivel and small enough hands you can get by with leaving the hood hinge in place. Some people punch a hole in the inner fender when then can't reach the lower right nut holding the heater box in place. I attached three photos. The first is what you are looking for sticking out of the firewall of your truck. These bolt like deals are clipped on to the heater box on the inside. They stick out of the firewall. The next two are for if anybody is curious what an Escort looks like without a dash. I just had to take a picture of my gutted car. And the pile of plastic I made while doing it. Attached Images __________________ '70 cab, '71 chassis, 383, TH350, NP205. '71 Malibu convertible '72 Malibu hard top Center City, MN

10-11-2005, 09:54 AM	#6
Rdub Registered User Join Date: Feb 2005 Location: Portland OR Posts: 74	Kaycee..... thanks that's great informantion. If I understand you correctly, on my AC truck, the heater core comes out from inside the cab as opposed to from under the hood. This would mean I don't need to remove the hood hinge and fender liner as written up in the FAQ but do need to remove the glove box, ducts, wiring and cables as you indicate.



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