jigmup

I have an '97 3500 with 310,000 miles on it. My problem is that I just can't get the cab to warm up. I have installed a new thermostat to try to keep the engine temp up but still get the same old up and down temps until I put a load behind it. I have cardboard between the radiator and the intercooler and this helps keep the engine temp up in the minus degree temps. The real problem is that the heater doesn't blow hot air. Even with the engine temp at 190 the air coming out of the heater is only warm at best. I have good air flow from the fan. I know of the problem with debris getting in the heater. Anyone know of a way to get this cleaned out with out tearing the whole dash apart? I've flushed the heater core. Any help would greatly appreciated.

nickg

turn your selector to re-circ, that improves heater out put , but may fog your windows.
My thermostat comes up to temp and takes a while for the temp to drop when idling, goes from 190 to 170 in maybe 15mins or so in -30 or better weather once driving (moving at any speed) it back to temp and stays there

mine had the evap core plugged with oily residue, but I had weak air flow, even thou the fan was blowing like mad