How good is the AC in these trucks? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

davepl · 08-17-2014, 07:03 PM

Reconnecting all of my AC stuff today, and although I've never had operational air, they did take their time to build a pretty nice system. I like how on max fan it runs straight 12V by relay, for example. And how it also supports fresh air, recirc, and so on. Other than a temp (like the Comfortron, which I assume wasn't an option) it really has everything.

Running it today it really moves some air, albeit room temperature for now.

I know the compressor is an older style, and R-134 may not work as well as R-12, but it's a small cab with a lot of airflow, so I'm curious how it compares to modern vehicles.

My Range Rover will push your hair back in all four seats while simultaneously pumping air through them, but I have reasonable expectations for a 40 year old truck, I think....

Andy4639 · 08-17-2014, 07:17 PM

Mine works well but on the lower settings I can barely feel the air movement. With some tweaking though it can run with the best of them. I have done away with the cowl vent. I sealed the flapper area off totally. I also made the passenger side vent inside the cab manual and it stays open all the time to recirc the cab air. I also installed a manual hot water valve to make sure no hot water runs through the heater and heats up the cab while the AC is running. I swaped everything over to 134a Freon years ago. The only thing now is if I could find a fan motor that would spin faster on the slower speeds.

**leddzepp** · 08-17-2014, 07:18 PM

My factory AC with R 12 will freeze you out of the cab sitting still in 110 degree heat.

davepl · 08-17-2014, 07:21 PM

If you wanted more airflow at low settings you could change the heater fan resistor. Just measure it and replace with lower ohm resistors.

Only thing is they are a dead load - they have to dissipate everything as heat, which is why they're made of coils and directly in the airflow path, I assume. So it's not like you could stick a 1/4W resistor in there. But maybe there are different ones out there. Maybe Cadillac had different ones, who knows? But that'd be the best way to do it short of someone making a fan more efficient at that voltage.

Andy4639 · 08-17-2014, 07:42 PM

Mine will keep the cab at 40* on a humid 90* and above day here in SC.
The lower speed settings are very weak in these year models no matter who's truck it is. On the lowest setting you will barely feel the air coming out of the drivers side ball vent.
I have thought about taking the motor and seeing if they can rewind it to get more RPM's out of it.

**FL71C10** · 08-17-2014, 08:33 PM

Now we are hopping up blower motors? You know you are a gear head when...

08-17-2014, 07:03 PM	#1
davepl Registered User Join Date: Aug 2006 Location: Redmond, WA Posts: 6,332	How good is the AC in these trucks? Reconnecting all of my AC stuff today, and although I've never had operational air, they did take their time to build a pretty nice system. I like how on max fan it runs straight 12V by relay, for example. And how it also supports fresh air, recirc, and so on. Other than a temp (like the Comfortron, which I assume wasn't an option) it really has everything. Running it today it really moves some air, albeit room temperature for now. I know the compressor is an older style, and R-134 may not work as well as R-12, but it's a small cab with a lot of airflow, so I'm curious how it compares to modern vehicles. My Range Rover will push your hair back in all four seats while simultaneously pumping air through them, but I have reasonable expectations for a 40 year old truck, I think.... __________________ 1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible

08-17-2014, 07:17 PM	#2
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Re: How good is the AC in these trucks? Mine works well but on the lower settings I can barely feel the air movement. With some tweaking though it can run with the best of them. I have done away with the cowl vent. I sealed the flapper area off totally. I also made the passenger side vent inside the cab manual and it stays open all the time to recirc the cab air. I also installed a manual hot water valve to make sure no hot water runs through the heater and heats up the cab while the AC is running. I swaped everything over to 134a Freon years ago. The only thing now is if I could find a fan motor that would spin faster on the slower speeds. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

08-17-2014, 07:18 PM	#3
leddzepp Moderator Join Date: May 2007 Location: Southern Cal Posts: 20,036	Re: How good is the AC in these trucks? My factory AC with R 12 will freeze you out of the cab sitting still in 110 degree heat. __________________ 1972 C/10 Cheyenne Super SWB. Restored, loaded, slammed. 1968 C/10 50th Anniversary LWB. Unrestored, stock, daily driver/work truck. RIP ElJay RIP 67ChevyRedneck RIP Grumpy Old Man RIP FleetsidePaul

08-17-2014, 07:21 PM	#4
davepl Registered User Join Date: Aug 2006 Location: Redmond, WA Posts: 6,332	Re: How good is the AC in these trucks? If you wanted more airflow at low settings you could change the heater fan resistor. Just measure it and replace with lower ohm resistors. Only thing is they are a dead load - they have to dissipate everything as heat, which is why they're made of coils and directly in the airflow path, I assume. So it's not like you could stick a 1/4W resistor in there. But maybe there are different ones out there. Maybe Cadillac had different ones, who knows? But that'd be the best way to do it short of someone making a fan more efficient at that voltage. __________________ 1970 GMC Sierra Grande Custom Camper - Built, not Bought 1969 Pontiac 2+2 427/390 4-speed Coupe 1969 Pontiac 2+2 427/390 4-speed Convertible

08-17-2014, 07:42 PM	#5
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Re: How good is the AC in these trucks? Mine will keep the cab at 40* on a humid 90* and above day here in SC. The lower speed settings are very weak in these year models no matter who's truck it is. On the lowest setting you will barely feel the air coming out of the drivers side ball vent. I have thought about taking the motor and seeing if they can rewind it to get more RPM's out of it. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

08-17-2014, 08:33 PM	#6
FL71C10 Senior Member Join Date: Jun 2010 Location: Orlando, Florida Posts: 2,509	Re: How good is the AC in these trucks? Now we are hopping up blower motors? You know you are a gear head when... __________________ 71 Chevy C10 Shortbed Stepside. LT1 with 4l60E. Just got back from painter, in assembly now.



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