2002 jeep liberty 3.7, heater blows only warm air. Changed themostat,flushed heater core...flows clean both ways, flushed radiator clean. All hoses to and from heater core are nice and hot about the same as all the rad. Hoses. It never overheated just low heat also checked the old themostat in a pot of water and that turned out to be good...opened right at 192

SOURCE: 2002 JEEP LIBERTY LIMITED RUNS HOT. CHANGED

hi, I had the same problem. change the fan relay and the wire molex to the relay. The wire molex is the most important part, because the the wire wears out from the heat. good luck

SOURCE: 94 jeep wrangler overheating

Have the cooling system pressure tested. If it holds pressure, that's a good thing. If it doesn't hold pressure, you may have a leaking head gasket. What may be happening is the crack in the head gasket could be blowing hot air into the cooling system causing it to overheat.

SOURCE: heater only blows warm air.

The hoses from your heater core should be very hot to the touch. Check the hoses going to the core from the water pump. It should be very hot. The return hose should also be very hot. Now check the hoses going to the core. If they are not the same temp, then your heater control valve is not working correctly or the vacuum is not working. At any rate, locate the vacuum line going to the heater valve. Remove the silver bar on the valve from the plastic plunger arm. You will have heat all the time now if it was only a vacuum problem. You can fix it later when it's warmer out. BTW a 200* thermostat will make your heater even hotter.

Paul W

• 404 Answers
• Posted on Feb 05, 2009

SOURCE: The heat in my 1992 Jeep Wangler is not working.

Hi!
It appears we have an Air lock scenario and you will need to perform a system Bleed.
Park the vehicle on level ground, when cold remove coolant filler cap, start engine and leave to idle, turn heater on full and blower to max. When engine reaches operating temperature watch and listen near coolant filler, keep clear as gurgling and hopefully a boil over should occur. Top up with very warm coolant and wait as it may do it again.
Check for heat inside vehicle if warm replace coolant cap but keep an eye on temperature gauge as the ~Air lock may have moved on from heater matrix/core so proceedure needs to be carried out again from COLD.
If persistent boil ups/over attention must made in the cylinder head
or gasket area, or possibly water pump?
Please press the Blue button to appraise my FREE Efforts, Thank You!
Paul 'W' U.K.

SOURCE: I have a 4cyl 1998

There is a heater control valve on the heater core hose. This is a common problem on the Jeep Wranglers. The valve is not opening.