Tip & How-To about 2006 Chevrolet Cavalier

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.

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My heater in my 2000 cadillac doesnt blow any air. Windows stay iced up

There are several answers however first would be do you have enough anti freeze in your radiator. If your cooling system is low on water heat will be very cool if an. Second check your heater core could be plugged or not working. Your vacuum sytem could have a problem which would cause your vents not to open properly. Try these first. good luck

Dec 06, 2016 | Cadillac Cars & Trucks

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heater blowing cold air

Feel the two heater hoses going from engine into the firewall. Both should be hot when the engine is at normal operating temperature-showing that the heater core is circulating coolant.
If both hoses are hot or warm at least, then your heater case doors are not operating properly. The temperature blend door that allows air to flow past the heater core and pick up heat is probably the culprit. Check on the case doors-they are probably vacuum operated. Watch for movement on the vacuum controllers as you work the controls. They're all different-figure out which are working and which one is not. Vacuum hoses go to little canisters. When vacuum is applied, the diaphragm in the canister pulls a lever inward on the canister's end. The canisters and levers are attached to the various doors, opening and closing them as demanded by the dash controls.
The vacuum for all this jerry-rigged stuff is a single vacuum hose from the engine, through the firewall, into the back of the HVAC control head, or heater controls, where a pod-like thing can distribute vacuum signals to several lines, often color coded, around the heater assembly case.

Nov 21, 2013 | Chrysler PT Cruiser Cars & Trucks

1 Answer

which is what I do to write the code P0420, as do I fix it? I change it?

So what is causing my P0420 code? There are a number of things that could be causing this p0420 catalyst efficiency code. The most common thing is the catalytic converter itself is no longer functioning properly. The other likely thing is the rear O2 (oxygen) sensor is no longer working properly. Other things could include exhaust leaks, damaged exhaust pipes, damaged O2 sensor wiring/connectors, plugged catalytic converter, etc.
OK, so I want to diagnose things, what do I do next? The easiest thing to do first is a visual check of things. Visually inspect the exhaust system for leaks, check the catalytic converter for dents, holes, severe discoloration, and check for a rattle inside. If any of those syptoms are there, the converter likely needs replacement. Then, visually inspect the downstream O2 sensor (behind the converter). Check for broken wires, obvious faults, etc. If all that checks out, you'll want to check the operation of the O2 sensor. To do that, you'll need access to a scan tool or oscilliscope. Check that the waveform is pretty steady. If the reading fluctuates then the sensor is likely bad and will need to be replaced.
On some vehicles such as some Subaru models an ECM reflash will fix the problem. As you can see a P0420 can be caused by many things, so if you have any doubts as to whether you can fix the problem yourself, please seek the advice of a professional technician. Good luck!

Answer found @ www.p0420.com

Jan 23, 2010 | 2002 Jaguar X-Type

1 Answer

Heater does not work properly. No heat at all

this is a common jeep problem a. k. a. a jeep thing . to fix the dash must be removed to gain axes to the heater /a/c box.replace p.o.s. temp control motor & your done.

Oct 15, 2009 | 2001 Jeep Grand Cherokee

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