not enough heat

1990 jeep cherokee laredo: Thermostat is new 210 degree, gauge confirms this. Air is warm at highway speeds, but not hot, air is cooler at lower speeds. Jeep has A/C. Is problem with heater core only option left?

If you're wanting warmer temps. for your heater, It would be best to use what the factory calls for and either buy a grill cover orput something in front of the radiator to block the wind.

1990 jeep cherokee laredo: Thermostat is new 210 degree, gauge confirms this. Air is warm at highway speeds, but not hot, air is cooler at lower speeds. Jeep has A/C. Is problem with heater core only option left?

There are some vacuum hoses that control the water valve at the heater core, and the fresh air/recirculating air gate. You might have a leak.

Note that on high fan speeds, the heat is NEVER hot. This is because the air is moving past the heater core so fast that it never gets a chance to heat up. Try low and medium fan speeds only.

Try blowing your heater core out with compressed air set to about 40lbs. Had this happen to a couple of vechiles. Heater core gets blocked and wont flow. Blew them out and heat!

Are you blowing the dirt out of the fins, or removing the heater hoses, and blowing gunk out of the water pipes in the core?

The method I was using was removing the the heater hoses and putting air to one end and putting a short section of hose on the other end into a bucket and blow out the heater core. Shouldnt use more than 40 lbs. If you use too much pressure could damage the core.

Check the heater hoses going to and from the heater core. Are they hot? If supply hose is hot and return is warm, the heater valve is (a) broken or (b) not getting a vacuum to activate. If it's the vacuum, I pulled the metal wire looking piece that works the heater valve and in-turn opened the valve wide open. Never had a heat problem since. I did this after replacing the control unit and it still didn't work.