1970 Suburban Rear AC - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Chevelle327 · 10-15-2007, 03:16 AM

Hello all, this is my first post. I just traded a 64 Galaxie 500 for a good condition, untouched 1970 GMC Suburban. It has factory Rear Air(possibly dealer installed). everything seems to be prettymuch untouched. However it don't work, actually its intermenten. Does anyone have a wiring diagram that would have this factory rear AC? Actually I'm not so sure REAR AC would be correct, it seems to be located at the very back window but its ducted all the way up front along the roof. Also, where is the cheapest place to get an assembly manual? Thanks in advance for any help.
Justin

earl87gta · 10-15-2007, 03:46 AM

From kingsport Tn .
rear AC was a factory option. I have never sean a wiring diagarm for for it. The witch is in the dash on the left side and the blower motor for it is int the vary back by the big window if you turn the switch on and it doesnt come on you may want to see if you are getting power at the blower motor. wish I new more on how it worked. Im sure some one on here will have a wiring diagram for it.

**uncle** · 10-15-2007, 05:23 AM

The switch on the 70 should be on the front of that assembly. The motor is under the very last cover at the rear.

Chevelle327 · 10-15-2007, 12:24 PM

There are two switches on the overhead control panel. One is rotory and says Off/Low/Med/Hi and there is also a toggle switch just to the rear of that and I don't know what that does, but I suspect that may have been installed by a previous owner. Is the rotory switch what engages the compressor clutch? Does power run straight from the fuse block to the switch, or does it have to pass through some other control device? What fuse would that be under? Sorry for all the questions, Hopefully I'll be able to contribute a little later, when I learn the vehicle better.
Thanks,
Justin

earl87gta · 10-15-2007, 12:48 PM

I im not 100 % on this but the compresor is turned on by the regular ac controls in the dash. the rear A/c is more of an air handler set up using the existing AC compresor . so you cant have just the back on the front has to be on too.

Chevelle327 · 10-15-2007, 02:46 PM

What's strange is that there doesn't appear to be any controls in the dash for the AC. the only controls in the dash are DEF, AIR FAN and HEAT and like most of these old trucks, the DEF lever has broken off sometime in the past. I was wondering if it wasn't similar to modern vehicles, for example... I can turn the rotory switch overhead to adjust fan speed, which would be very helpfull for moving air throughout the truck, and then maybe that toggle switch I have my doubts about actually turns on the compressor for AC. Just a thought, but sounds logical. Does anyone actually have a 70 model with rear air?
Thanks for the input so far,
Justin

**uncle** · 10-15-2007, 03:34 PM

Earl87gta, you are referring to a 72 Sub. It's the only year w/front and rear a/c, unless someone has changed it.

earl87gta · 10-15-2007, 04:19 PM

Thanks I was thinking they were all the same when it came to that . I bet the togle switch some one added to his was what they were using to turn it off and on.

Robert1970C20rstbukt · 10-15-2007, 08:13 PM

My K/20 Suburban has the same system you have. There's no A/C controls in the dash, just the overhead rotary switch. It has a standard heater control in the dash with no front A/C. When you turn the blower switch on hi, medium, or low the clutch kicks in and the blowers come on. It doesn't work now(practically all the under-hood parts are gone) but the brother of the PO told me that's how it worked.

Chevelle327 · 10-16-2007, 12:07 AM

As it turns out, the toggle switch was added afterwards. If the fan switch it turned on, then you can use the toggle switch to engage the compressor for AC. Now I have a problem that the rear fan only works in low and medium. when I turn it to hi, I hear a click in the very back, but the fan does not speed up. any thoughts on that? Also, can you purchase the plastic ducting? the bottom portion is in good shape, however the upper portion that attaches to the roof is cracked all over and very brittle, do they offer them as serperate peices?
Thanks,
Justin

earl87gta · 10-16-2007, 12:12 AM

no one makes replacment parts for these wish they did i would by one for my burb i would love to have rear air in it. Sonds like a relay is not working when it goes in to high. Is the fan motor making the noise or is it a relay clinking sound.

10-15-2007, 03:16 AM	#1
Chevelle327 Registered User Join Date: Oct 2007 Location: Summertown, TN Posts: 4	1970 Suburban Rear AC Hello all, this is my first post. I just traded a 64 Galaxie 500 for a good condition, untouched 1970 GMC Suburban. It has factory Rear Air(possibly dealer installed). everything seems to be prettymuch untouched. However it don't work, actually its intermenten. Does anyone have a wiring diagram that would have this factory rear AC? Actually I'm not so sure REAR AC would be correct, it seems to be located at the very back window but its ducted all the way up front along the roof. Also, where is the cheapest place to get an assembly manual? Thanks in advance for any help. Justin

10-15-2007, 03:46 AM	#2
earl87gta Senior Member Join Date: Dec 2003 Location: Kingsport TN Posts: 4,641	Re: 1970 Suburban Rear AC From kingsport Tn . rear AC was a factory option. I have never sean a wiring diagarm for for it. The witch is in the dash on the left side and the blower motor for it is int the vary back by the big window if you turn the switch on and it doesnt come on you may want to see if you are getting power at the blower motor. wish I new more on how it worked. Im sure some one on here will have a wiring diagram for it. __________________ Earl 68 2500 4x4 GMC Burb

10-15-2007, 05:23 AM	#3
uncle Senior Member Join Date: Aug 2003 Location: Conyers,Ga. Posts: 7,288	Re: 1970 Suburban Rear AC The switch on the 70 should be on the front of that assembly. The motor is under the very last cover at the rear.

10-15-2007, 12:24 PM	#4
Chevelle327 Registered User Join Date: Oct 2007 Location: Summertown, TN Posts: 4	Re: 1970 Suburban Rear AC There are two switches on the overhead control panel. One is rotory and says Off/Low/Med/Hi and there is also a toggle switch just to the rear of that and I don't know what that does, but I suspect that may have been installed by a previous owner. Is the rotory switch what engages the compressor clutch? Does power run straight from the fuse block to the switch, or does it have to pass through some other control device? What fuse would that be under? Sorry for all the questions, Hopefully I'll be able to contribute a little later, when I learn the vehicle better. Thanks, Justin

10-15-2007, 12:48 PM	#5
earl87gta Senior Member Join Date: Dec 2003 Location: Kingsport TN Posts: 4,641	Re: 1970 Suburban Rear AC I im not 100 % on this but the compresor is turned on by the regular ac controls in the dash. the rear A/c is more of an air handler set up using the existing AC compresor . so you cant have just the back on the front has to be on too. __________________ Earl 68 2500 4x4 GMC Burb

10-15-2007, 02:46 PM	#6
Chevelle327 Registered User Join Date: Oct 2007 Location: Summertown, TN Posts: 4	Re: 1970 Suburban Rear AC What's strange is that there doesn't appear to be any controls in the dash for the AC. the only controls in the dash are DEF, AIR FAN and HEAT and like most of these old trucks, the DEF lever has broken off sometime in the past. I was wondering if it wasn't similar to modern vehicles, for example... I can turn the rotory switch overhead to adjust fan speed, which would be very helpfull for moving air throughout the truck, and then maybe that toggle switch I have my doubts about actually turns on the compressor for AC. Just a thought, but sounds logical. Does anyone actually have a 70 model with rear air? Thanks for the input so far, Justin

10-15-2007, 03:34 PM	#7
uncle Senior Member Join Date: Aug 2003 Location: Conyers,Ga. Posts: 7,288	Re: 1970 Suburban Rear AC Earl87gta, you are referring to a 72 Sub. It's the only year w/front and rear a/c, unless someone has changed it.

10-15-2007, 04:19 PM	#8
earl87gta Senior Member Join Date: Dec 2003 Location: Kingsport TN Posts: 4,641	Re: 1970 Suburban Rear AC Thanks I was thinking they were all the same when it came to that . I bet the togle switch some one added to his was what they were using to turn it off and on. __________________ Earl 68 2500 4x4 GMC Burb

10-15-2007, 08:13 PM	#9
Robert1970C20rstbukt Registered User Join Date: Jun 2004 Location: Beeville, Texas Posts: 1,943	Re: 1970 Suburban Rear AC My K/20 Suburban has the same system you have. There's no A/C controls in the dash, just the overhead rotary switch. It has a standard heater control in the dash with no front A/C. When you turn the blower switch on hi, medium, or low the clutch kicks in and the blowers come on. It doesn't work now(practically all the under-hood parts are gone) but the brother of the PO told me that's how it worked. __________________ RJD 1984 Chevrolet C30 welding truck 454/SM465 1977 GMC C15 pickup 350/TH350 1970 Chevrolet C20 pickup 350/TH400 1970 Chevrolet K20 Suburban 454/TH350 1969 GMC 8500 478M V6/5 spd winch truck

10-16-2007, 12:07 AM	#10
Chevelle327 Registered User Join Date: Oct 2007 Location: Summertown, TN Posts: 4	Re: 1970 Suburban Rear AC As it turns out, the toggle switch was added afterwards. If the fan switch it turned on, then you can use the toggle switch to engage the compressor for AC. Now I have a problem that the rear fan only works in low and medium. when I turn it to hi, I hear a click in the very back, but the fan does not speed up. any thoughts on that? Also, can you purchase the plastic ducting? the bottom portion is in good shape, however the upper portion that attaches to the roof is cracked all over and very brittle, do they offer them as serperate peices? Thanks, Justin

10-16-2007, 12:12 AM	#11
earl87gta Senior Member Join Date: Dec 2003 Location: Kingsport TN Posts: 4,641	Re: 1970 Suburban Rear AC no one makes replacment parts for these wish they did i would by one for my burb i would love to have rear air in it. Sonds like a relay is not working when it goes in to high. Is the fan motor making the noise or is it a relay clinking sound. __________________ Earl 68 2500 4x4 GMC Burb



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