What did you do with your GMT400 today...or yesterday....

[Big T]

Arrived at Montana home and had a delivery of a new HVAC control unit for the ‘99 Suburban. Old one stopped working properly. Fan was always on, no matter the position and there was no change in speed. New one installed in minutes and back to working normal.

 

[Will L.]

Arrived at Montana home and had a delivery of a new HVAC control unit for the ‘99 Suburban. Old one stopped working properly. Fan was always on, no matter the position and there was no change in speed. New one installed in minutes and back to working normal.

View attachment 99860

Do you by chance still have the part number handy? It is the same controller used in the 96.5 and newer Hummers, and is part of a desired upgrade for the older ones.

My 95 uses a 93 truck controller and afaik many other related parts for the ac system.

 

[Big T]

Do you by chance still have the part number handy? It is the same controller used in the 96.5 and newer Hummers, and is part of a desired upgrade for the older ones.

My 95 uses a 93 truck controller and afaik many other related parts for the ac system.

I have it, but they have different units depending on whether you have rear window defogger, which the Suburban does. It’s a unit by SKP, so it’s Chinese.

 

[Will L.]

Ok, I missed that. There are some Hummers that have defogger lines in the windshields, but idk if that is where their controllers are

 

[Big T]

Ok, I missed that. There are some Hummers that have defogger lines in the windshields, but idk if that is where their controllers are

I ordered off your hated RockAuto, but SKP is Hecho in China anyway. I think you would need the SKP w/o the rear window defogger for the Hummer.

 

[dbrannon79]

iirc those controllers have a serviceable blower switch that can be replaced. I like the way GM did the older units by putting relays above the ac box for each fan speed which took the load off the blower switch. my 95 only has one relay for the high fan speed, everything else runs through the resistor and straight to the switch to carry the load.

I modified a controller from a 96 or 97 rig to work in my 95 since those are a one year only and are hard to find and high priced. it was simple to wire in after getting the connectors from the newer rig I pulled the controller from. some day I plan to wire in three more relays between the resistor and the blower switch to take the load off. same concept we use on the OPS sensor with the lift pump.

 

[ak diesel driver]

I saw an adapter harness on Amazon for doing that