Question about 1990 Subaru Legacy

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Heater and airconditioner work half time thermometer varies

Temperature guage will go to middle, then back to cold. Heater and air-conditioner only work when car has been running for a long time. On longer drives(30-50) miles, the radiater will get to hat and the anti-freeze will boil out of the overflow cap. Someone told me that it sounds like the thermostat is out. Does this sound right to you. 1990 subaru legacy wagon

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It could be the thermostat (simple fix), check this first, Then i would go for the water pump but worst scenario would be the head gasket gone, Have a pressure test done on the car to eliminate this, Hope this helps

Posted on Dec 10, 2008

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My air condition only blows out cold air not hot

Turn your air conditioner OFF and turn your heater ON. Air conditioners were designed to blow out one temperature of air... COLD.

Nov 13, 2014 | 2004 Mercury Grand Marquis


Why Is My Heater Cold?

This is a very common question that does not have a single answer. There are several things that can cause your heater to not work properly. The object of this article is to help you to determine which part of your heater system is causing your particular problem.

First, you must understand that the heater is part of your engine cooling system. Then, it also has its own parts inside the vehicle that have absolutely nothing to do with the engine cooling system. The trick to getting your heater working is to first determine which part of the heater system has the problem.

The first step is to verify proper engine cooling system operation. There is more to this than just replacing a thermostat (like many people will probably tell you to do). If you have a problem like a blown head gasket or a defective water pump, your heater will not work. What SHOULD be done is to operate the engine while watching the computer data for the engine coolant temperature sensor (ECT). Doing this, you can verify that the engine is warming up to operating temperature. You can also verify that the thermostat is opening at the correct temperature by watching the computer data. The engine temperature will drop when the thermostat opens.

Then, use an infrared thermometer to take a manual temperature reading from the engine near the temperature sensor. The reading you get from the thermometer should be within about 5 degrees of the reading that the computer is getting from the ECT sensor.

You can also see when the thermostat opens by using the thermometer. The radiator hoses and radiator tanks should not start getting hot before the temperature of the thermostat housing is between 187 and 195 Deg. F (87 to 90 Deg. C). Checking thermostat operation in this way will eliminate unnecessarily replacing the thermostat if it is working correctly.

Also check for a clogged-up heater core by taking the temperature of the heater inlet and outlet hoses. The inlet hose should be within about 10 Deg. of the thermostat housing temperature. The outlet hose is normally 20 to 30 Deg. cooler than the inlet hose. If the outlet hose is much cooler than this, there is most likely a restriction in your heater core.

The engine cooling fans should come on between 220 and 228 Deg. F (104 - 108 Deg. C). When they do come on, the air that is blowing through the radiator should be HOT. If it is not, this is an indication that the radiator is stopped up, the water pump is not pumping correctly, or there is a blown head gasket that is filling your cooling system with combustion gasses.

If you do not have access to a scan tool that can read live engine data, all of this can be done with just the thermometer, but it is best to also verify the computer ECT data.

Please note
that a pretty good infrared thermometer can be purchased at most any auto parts outlet for around $40 (US). It is a good investment because you can use it for many other things and it costs about half as much as an hour of diagnostic time at most shops. For most automotive purposes, you need one that can read from 0 to 700 Deg. F (-10 to 370 Deg. C).

If the engine cooling system is working properly, it is time to look INSIDE the car for the problem. The blend-air door in your A/C-heater housing may not be working. When you switch the temperature control inside the car, you should be able to HEAR a change in the air flow. This applies to ALL vehicles, whether they are equipped with cable, vacuum, or electronically-controlled blend-air doors. If you cannot hear a difference in the sound of the air moving through the A/C-heater housing when the temperature controls are moved from HOT to COLD and back again, then chances are pretty good that the problem is with your blend-air door.

The actual problems that can occur with the blend-air door varies depending upon what type of system your vehicle is equipped with. It could be a disconnected or "out-of-adjustment" cable on cable-controlled doors. It could be a bad vacuum servo, broken vacuum line, or malfunctioning vacuum switching valve on vacuum-controlled systems. It could be a defective electronic blend-air door actuator or a bad electronic control unit on electronically-controlled HVAC units. It could also be that the blend-air door itself is broken on any of these systems.

If your engine cooling system is functioning correctly and you think you may have a blend-air door problem, it is probably best to get it checked by a professional that has the information, equipment and knowledge to check it out. Broken blend-air doors and defective blend-air door actuators are fairly common and often require removal of the instrument panel to repair them.

on Dec 06, 2011 | 2006 Chevrolet Cavalier

1 Answer

My heat does not work

Make sure that your radiator is filled to the proper level. If it isn't, the heater core may not be filled, so no heat can be extracted from it.

Apr 18, 2014 | 2000 Lincoln LS

1 Answer

Heater blows cold air and the temperature guage reads cold after driving for 20 minutes

Best case scenario is your thermostat is stuck open. When this happens the engine will take a long time to warm up and will never get up to full temp. Worst case could be a serious problem such as a blown head gasket. If there is no coolent in the engine the temp gauge will not register either.

Dec 15, 2013 | 1999 Ford Explorer

1 Answer

2006 grand prix heater only blows cold air. both heater hoses are hot blower motor works fine.

Sounds like the temperature blend door actuator may be bad or the vacuum hose to it is disconnected.

Poor Heater System Performance CAUTION
Check all fluid levels and adjust as needed, before operating vehicle for extended periods at idle.
  1. Start the engine.
  2. Idle the engine until the thermostat opens (upper radiator hose will be hot) Is the engine at normal operating temperature (approx. 200° F)? If yes, go to the next step. If no, go to step 16.
  3. Set the mode selector to FLOOR mode.
  4. Set the heater control selector to the warmest temperature setting.
  5. Set the blower speed the lowest setting.
  6. Carefully feel the inlet and outlet heater hoses at the heater core. Is the inlet heater hose significantly hotter than the outlet heater hose? If yes, go to step 14. If no, go to the next step.
  7. Set the mode selector to PANEL mode.
  8. Select the maximum blower speed.
  9. Select the warmest temperature setting.
  10. Place a thermometer into the center I/P PANEL air outlet and affix a second thermometer to the heater core outlet heater hose.
  11. Record the temperature at the center I/P PANEL air outlet and at the heater core outlet heater hose. Are the two temperature readings about equal? If yes, go to the next step. If no, go to step 13.
  12. Inspect and repair the cowl, cowl area, recirculation door, and the HVAC evaporator/heater core case for cold air leaks. Repair any problems found, go to step 17.
  13. Inspect the temperature door operation. Repair any problems found, go to step 17.
  14. Turn OFF the engine. Back-flush the heater core. Start the engine. Select the FLOOR mode and the lowest blower speed. Select the warmest temperature setting. Feel the temperature of the inlet and outlet heater hoses at the heater core. Is the inlet heater hose feel significantly hotter than the outlet heater hose? If yes, go to the next step. If no, go to step 17.
  15. Replace the heater core. When the repair is completed, go to step 17.
  16. Check for low engine temperature problems, Repair or replace as needed, go to step 17.
  17. Operate the system in order to verify the repair. If the system operates properly, the repair is complete. If the heater still does not work properly, repeat the entire procedure.

Nov 19, 2010 | 2006 Pontiac Grand Prix

2 Answers

Heater not working it is blowing cold air at all times is there a

Heater blowing cold air until I get on the interstate, then it works; however, when I stop at lights it starts blowing cold air again. The temperature gauge will be in the middle but the car will still be cold until the car starts moving.

Nov 14, 2009 | 2002 Jaguar X-Type

1 Answer

Rear airconditioner blowing hot air


Jun 13, 2009 | 2000 Ford Econoline

1 Answer

1999 Mercedes e-320 Heater (blows cold air)

Hi there,
firstly why did you replace the water pump, would i be correct in thinking that it broke, if so, when you took it out was there damage to the impellor, usually there is and these bits of debris have to be retreived. the hot air in your car comes from a heater matrix that is seperate to the main radiator the cause of your problem could be explained by loose debris blocking the heater matrix inlet, also that debris could fall back down and destroy the impellor on the new pump.
If the impellor completely broke up then it will be debris in the system this should be fixed asap to safeguard the new pump.

Apr 13, 2009 | 1999 Mercedes-Benz E-Class

1 Answer

The air conditioner continues to run even when the heater should

that is your servo motor that controls the cold or hot flap. its abou a 50$ part

Mar 11, 2009 | 2001 Ford Taurus

3 Answers

My heater is not blowing hot air, the air conditioner seems to be working, I replaced the heater and airconditioner switch module but it didn't help

I have a 2001 ford winstar and my heater is not working I slide the ac/heater switch to heat and all it does is let out a thumping sound and blow cold air out and it is starting to get cold in the morning

Jul 27, 2008 | 2001 Ford Windstar

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