On my 98 k1500 that I just got I’m having some issues with hvac. 1. As I turn on the fan speed it don’t turn on unless it’s set to highest speed. 2. Hot/Cold knob doesn’t seem to get hot wouldn’t say cold neither just blows air. 3. No matter which position I set the blend door to air is blowing out of every vent including defrost. So what all needs to be replaced or fixed please don’t tell me I gotta replace the hvac box!! No noises are being made as I switch it on just blows straight air. Now when I push the A/C button there is a rattling noise coming from the blower motor area.. Any help is appreciated thanks in advance!
Actuator or HVAC box?
- Thread starter h3ad tr9p
- Start date
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The fan speed issue is possibly the resistor assembly, they are inexpensive. Usually the bushings are bad in the fan which caused the thermal fuse in the resistor assembly to fail. The other issues are possibly the actuators the mode and blend door. Several good you tube videos on replacing them. Before replacing actuators verify the linkages aren’t broken or stuck from sitting.
I had it running earlier and flipped through the floor to defrost settings the arm was moving to the one by the accelerator. That’s why I was thinking the hvac box doors might be stuck
AK49BWL
GMT400 Forever!
You can actually move the arms with the actuator still in place, just pull the spring out of the linkages and remove the white clips. A lot simpler than taking the whole actuator assembly off. The doors are also moveable while still intact, just a little more limited.
If everything is still there, the real problem is more likely to be that your mode doors have lost all their rubber edge seals, so no matter what position they're in, air still gets by. The upper two doors and the lower mode door are still sold, the lower as the door alone and the uppers as an assembly... You will have to remove the HVAC box to replace the uppers, but I don't believe it's necessary to do that for the lower. As for the temp door and air intake door... I was unable to find replacements anywhere for them, but mine were still intact.
In the under-hood fuse box, there's a 40A maxí-fuse for the blower. Replace it with a 25A fuse. If that fuse blows, replace your blower because it's drawing too much current and will continue to burn out resistor packs. Mine with a new motor maxes out at 16 amps starting up and hangs around 11-12 running full speed.
If everything is still there, the real problem is more likely to be that your mode doors have lost all their rubber edge seals, so no matter what position they're in, air still gets by. The upper two doors and the lower mode door are still sold, the lower as the door alone and the uppers as an assembly... You will have to remove the HVAC box to replace the uppers, but I don't believe it's necessary to do that for the lower. As for the temp door and air intake door... I was unable to find replacements anywhere for them, but mine were still intact.
In the under-hood fuse box, there's a 40A maxí-fuse for the blower. Replace it with a 25A fuse. If that fuse blows, replace your blower because it's drawing too much current and will continue to burn out resistor packs. Mine with a new motor maxes out at 16 amps starting up and hangs around 11-12 running full speed.
I will check that out tomorrow
