heat only on vent

[jgraybeal]

99 se, flushed entire cooling system, disconected heater core and flushed. Thought that would fix...wrong. Still no heat. Can rotate knob from a/c to defrost and can only get heat on vent setting...Please help.

[wijim]

Wierd. I just recently discovered that when I turn on the defogger or defogger/lower in my '98 SE, the AC kicks in. Must be a bad switch somewhere.

Jim

[wijim]

Ok. Just checked the owners' manual. It says the AC is DESIGNED to kick in in all modes except vent and lower WHEN the outside temperature is above 50 degrees. Glad I joined this forum. I'm learning alot just by talking to myself.

[lectraplayer]

Originally Posted by wijim

Ok. Just checked the owners' manual. It says the AC is DESIGNED to kick in in all modes except vent and lower WHEN the outside temperature is above 50 degrees. Glad I joined this forum. I'm learning alot just by talking to myself.

No heat anywhere? I assume that it's an electrical heat engage (the heater's electrically controlled vs. mechanical like some older cars). I think mine's the same way and was wondering why I had lost my heater, coolant leak for me). Check your coolant level. If it's bad low, you won't have any flow through your heater coil until you fill the radiator up. Check for leaks at this time if that's the problem as well to keep the water in. If not, check to see that whatever valve controls flow through the heater coil is working properly. If it doesn't investigate replacing it. I assume that what you meant by "flush" whas done to your radiator and engine, which affects but still bypasses the heater coil until you turn the heater on. This is why you should always turn the heater on when changing the fluids in your radiator.

I'm hoping it's a stuck valve problem. It should be very easy to replace. Just remember to drain your radiator and leave the drain open as you work on your heater. If you have heat in any one position on the controls, then I would investigate starting at that switch. You should have heat available in all positions except for "off". I even have heat available when in AC or Max AC, useful when I want the air less humid, but not so cold.

[cob206]

Read the threads about the blend door/belnd door actuator. A very common problem from what I'm finding out. Does your AC blow cold? If not, blend door operation could be a problem.

[jgraybeal]

I suspected a blend door problem after reading the threads, but a local ford dealer said i had more than one blend door... another dealer wanted to replace my water pump as a fix ($400.00). What could cause hot air to blow on vent setting only? BTW, I don't have auto climate control.

[lectraplayer]

Originally Posted by jgraybeal

I suspected a blend door problem after reading the threads, but a local ford dealer said i had more than one blend door... another dealer wanted to replace my water pump as a fix ($400.00). What could cause hot air to blow on vent setting only? BTW, I don't have auto climate control.

Start at the selector knob (the leftmost one, with vent, AC, floor, defog, etc.) and be sure you have electrical continuity toward the heater coil. Also, does the fan work on all the settings? If the fan also only works on Vent setting, that could be a starting point.

[jgraybeal]

My fan does work on all settings, and the A/C works great. I'm not sure how to check the selector switch. If I understand this car's cooling system, there is no valve to control the coolant flow thru the heater core. Coolant flows thru all the time and heat is directed into the car by a blend door. (Or Doors). This one has me stumped.

[lectraplayer]

I'm just not sure how it conveys your control of how much water to let through the heater coil, whather it's done with mechanical linkages or is done with a type of solenoid that's controlled by a potentiometer (what it feels like). I would suspect that if it's the potentiometer/solenoid method, the selector switch activates it when it isn't in the off position. This leaves me wondering if the appropriate circuit for that isn't making contact in areas other than vent. I actually have no idea either, as I haven't looked at how mine works, but maybe we can stumble on top of it in our discussion.