temp controller - The 1947 - Present Chevrolet & GMC Truck Message Board Network

beauhoward · 07-25-2014, 06:10 PM

Hi I am wondering if anyone has seen this temperature control installed in these trucks I have an 81 c10 im trying to convert it back to stock and figure out wiring issue any help is appreciated.

**hatzie** · 07-25-2014, 07:00 PM

RH picture looks like you have a chunk of the steel dash and definitely some of the bezel missing where the A/C controls used to bolt in.

In the LH picture it looks like someone completely disassembled the A/C control unit.
If you don't have all the pieces you'll need to find a complete one in a yard.

Left switch is the blower motor switch.
Center??? Does it have a cable attached? If so it might be the temp control.
Left is the Vacuum Mode selector switch. Be careful of those hoses. Be sure to hook them up to the same locations on the new control head and take care not to crunch them up or you'll have leaks.

The 1981 GM Light Truck service manual has a lot on the AC system in Chapter 10.
Schematics are in the back of the service manual.
Download all of the 81 service manuals at the link in my signature.

beauhoward · 07-25-2014, 07:08 PM

It doesn't seem to have steel missing from the dash but the bezeling was broken and removed. I have ordered the stock temperature control unit from lmc for this truck. It appears to only need the switch that was on the left and two cables which are both installed but pushed back in the dash so you can't see them in the pictures. I'm not sure what wires need to be removed or changed to convert this back to the stock installation. i'm also confused as to why it would be switched to have three switches and not have had the cables installed because I don't see how the blocker doors could open or close this way.

**hatzie** · 07-26-2014, 09:21 AM

I believe there should only be one cable for the Temp selector lever and door.
All the other doors in the A/C system are controlled with vacuum. The vacuum "Switch" on the left is actually the mode lever that selects MAX AC to DEF.

beauhoward · 07-30-2014, 06:55 AM

So I figured out my confusion.. The previous owner partially turned this truck into air conditioned when from factory it was only heated. I am considering altering his install and using a toggle switch to control compressor and getting an accumilator that i can install a binary pressure switch im not sure what size relay to use for toggle switch and compressor wiring. What are your opinions on this? Switching this to a factory ac would be expensive and a lot of work, also an aftermarket system is very expensive.

beauhoward · 07-30-2014, 07:15 AM

here are some pics

**hatzie** · 07-30-2014, 12:21 PM

5 pin 40A Mini ISO relay will switch the compressor clutch.

The dangling mode control switch had vacuum lines attached. What did the PO use for a heater AC box?
Is the evaporator already one of those under dash units?

07-25-2014, 06:10 PM	#1
beauhoward Registered User Join Date: Jul 2014 Location: charleston Posts: 4	temp controller Hi I am wondering if anyone has seen this temperature control installed in these trucks I have an 81 c10 im trying to convert it back to stock and figure out wiring issue any help is appreciated. Attached Images

07-25-2014, 07:00 PM	#2
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,932	Re: temp controller RH picture looks like you have a chunk of the steel dash and definitely some of the bezel missing where the A/C controls used to bolt in. In the LH picture it looks like someone completely disassembled the A/C control unit. If you don't have all the pieces you'll need to find a complete one in a yard. Left switch is the blower motor switch. Center??? Does it have a cable attached? If so it might be the temp control. Left is the Vacuum Mode selector switch. Be careful of those hoses. Be sure to hook them up to the same locations on the new control head and take care not to crunch them up or you'll have leaks. The 1981 GM Light Truck service manual has a lot on the AC system in Chapter 10. Schematics are in the back of the service manual. Download all of the 81 service manuals at the link in my signature. __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

07-25-2014, 07:08 PM	#3
beauhoward Registered User Join Date: Jul 2014 Location: charleston Posts: 4	Re: temp controller It doesn't seem to have steel missing from the dash but the bezeling was broken and removed. I have ordered the stock temperature control unit from lmc for this truck. It appears to only need the switch that was on the left and two cables which are both installed but pushed back in the dash so you can't see them in the pictures. I'm not sure what wires need to be removed or changed to convert this back to the stock installation. i'm also confused as to why it would be switched to have three switches and not have had the cables installed because I don't see how the blocker doors could open or close this way.

07-26-2014, 09:21 AM	#4
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,932	Re: temp controller I believe there should only be one cable for the Temp selector lever and door. All the other doors in the A/C system are controlled with vacuum. The vacuum "Switch" on the left is actually the mode lever that selects MAX AC to DEF. __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful. Last edited by hatzie; 07-26-2014 at 02:52 PM.

07-30-2014, 06:55 AM	#5
beauhoward Registered User Join Date: Jul 2014 Location: charleston Posts: 4	Re: temp controller So I figured out my confusion.. The previous owner partially turned this truck into air conditioned when from factory it was only heated. I am considering altering his install and using a toggle switch to control compressor and getting an accumilator that i can install a binary pressure switch im not sure what size relay to use for toggle switch and compressor wiring. What are your opinions on this? Switching this to a factory ac would be expensive and a lot of work, also an aftermarket system is very expensive.

07-30-2014, 07:15 AM	#6
beauhoward Registered User Join Date: Jul 2014 Location: charleston Posts: 4	Re: temp controller here are some pics Attached Images

07-30-2014, 12:21 PM	#7
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,932	Re: temp controller 5 pin 40A Mini ISO relay will switch the compressor clutch. The dangling mode control switch had vacuum lines attached. What did the PO use for a heater AC box? Is the evaporator already one of those under dash units? __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.



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