94 Ranger Heat Issues

I have some heat (barely) if I keep the fan on low or just above. If I put it on high, or one click below high it just blows cold air.



I have had everything heating related fixed within the last 3 years. The first time the heat went out (also had a leaky radiator) was about 3 years ago and my brother and dad replaced the radiator and heater core. The heat worked great, and it didn’t overheat until the water pump needed to be replaced, last year.



I went to a mechanic who ended up replacing everything (except the heater core and radiator) and my heat just barely works. He had to do some of the jobs like the thermostat and seals several times to get it right so I suspect anything he did. Any ideas? Thanks!

If he used a failsafe thermostat, they are notorious for locking in the open (failsafe) position well before overheating.

Determine the actual operating temperature using an infrared thermometer on the thermostat housing after it has warmed up to full operating temperature and report that temperature and we’ll go from there.