94 Wagon with heater problems

[Duncan1]

We have a very nice 94 wagon and last winter the heater worked absolutely fine. This year we are getting hardly any heat... I checked the temps on all hoses and the pump with a laser thermometer and they all look good. The coolant going into the heater is only a little warmer than the return line. 126k on it... Thanks

[Musician423]

What have you done so far?

Thermostat good? If your send and return heater hoses are hot to the touch, then maybe problem is in dash? Temperature control knob? Control
assembly may have failed and the flap isn't fully opening or closing?

Also, make sure A/C isn't running. Sometimes a relay can fail and therefore
your A/C compressor will be running even if you don't have A/C powered on inside your car.

I would turn temperature knob fast to see if you hear a flap closing. As in quickly turn knob from coldest cold to hottest hot. On my 1994 caprice, if you do it fast enough, you can hear a flap sound inside dash. No sound might mean flap isn't functioning, diluting hot air with escaping col air.

Also, if you recently winterized car and changed coolant, you might have air bubbles in system. Then you need to purge air via valve on top of thermostat housing

Good luck!

[Duncan1]

Thanks. I'll try these ideas.

[HLandin]

In reference to the flapper door, I believe the door is vacuum operated. If the hose is broken or does not have enough vacuum, the door might not operate.