No heat on 2000 Astro LS Rwd, 160,000 miles

[tahoeguy2000]

I have had no heat blowing thru any of the vents for the last few days.

I have noticed the temp gauge taking a while to move up to the 45 degree mark on the gage and the coolant level having to be topped up in the reserve tank quite often, not sure if this is related to the no heat problem.

The fan speed switch only worked in the first 2 settings. Air flow direction works and gets directed in all the settings in the past.

Had a spare switch assemble panel from the wreckers, pulled the dash board face plate off and replaced the switch panel this evening. But still no air blowing in heat or AC mode.

does anybody know if this is a blower motor issue or something like a relay or resistor problem. And how would I go about solving it.

Thanks in advance.

[old_master]

Intake manifold gaskets are a known problem with the 4.3L engine. That might be your coolant loss. Have the cooling system pressure tested and checked for leaks. Normal engine operating temperature should be very close to 200 degrees.

Check this thread in regards to the blower problem:
http://www.automotiveforums.com/vbul...d.php?t=771630

The thread is in the Blazer section, but wire colors and function is the same as your Astro, with one exception, the blower resistor and relay might be one part on yours.

If air flow does not come out where it should, check the vacuum line from the PCV valve to the HVAC Tee/check valve. They have a habit of dry roting and cracking where they cross over the engine.