Heater never gets warm?

NICKHEAD551

MEMBER
1999 PLYMOUTH BREEZE
2.4L
4 CYL
2WD
AUTOMATIC
97,000 MILES

I can drive twenty miles and no heat and temperature gauge on dash never moves. I had 2 mechanics tell me nothing was wrong thermostat. The third time I told mechanic to replace it anyway. Did not work. During the summer, everything is okay.

Thursday, February 13th, 2025 AT 6:06 PM

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
51,685 POSTS

It sounds like you may have two problems, first I would put a scanner on it to see what the engine temperature is, which when hot, it should be about 198 degrees. If not replace the sensor, here is the location which should fix the gauge problem, next with the heater issue when the engine is hot can you grasp the heater hoses to see if they are hot as well? Please go over this video which can help:

https://www.youtube.com/watch?v=SNRb6pSwYuU

You could have air stuck in the core as well or the core is clogged. I would remove the heater hoses and then use a garden hose to flush the core out, this works really well. When you work the temperature controls can you hear the blend door moving inside the HVAC plenum? Please check out the images below and let us know how it goes.

Images (Click to make bigger)