What would make a car heater only work on high?

Question:
My car heat and air condition will onl workon highest setting. Also my defrost will not work at all. I am really concerned being that it is about to snow. Any ideas what could cause this, it seems odd to me?

Answers:

what do i torque my head bolts to on my ford 400m?

You need a new blower resistor by the sounds of things. When you select the three lower speed settings, the current supplied to power up the blower motor goes through the resistor, to slow the speed of the blower motor down. When the high speed is selected, the resistor is bypassed, and full current is passed to the blower. The cause of your defroster not working, can either be the switch (does the amber light illuminate when you attempt to operate it?), the relay, or an open circuit somewhere. Hope this helps.

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What happens to a car with too much oil in the engine?

needs a new switch

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there is a clunking noise in my 02 envoy in the front end it happens when i go over bumps.?

You need a new switch inside, where the knobs to work everything are. That should take care of it, also, maybe check your fuses,

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Car oil filters - how do you know what kind to get?

You probably have a bad switch

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Does any one know if the heated seats on a 2001 Lexus is on a fuse?

The swich has failed.Need to replace it.Good luck.

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How much power consumption does a car battery charger use?

your switch is probably bad for the heat settings,check the fuse for rear defroster,also check connection on window,might be loose or corroded.

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i changed the glow plugs on my citreon xantia yesterday and now its going dead slow!! any ideas?

there is a resister in the heat ducks that controls the fan speed
most the time that's the fix $12.00 at a parts store.

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My 88 F-250's cold start problem.?

Or the blower speed resistors have burnt out.For the defrost, the damper door that directs flow is not operating.

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i have a 1998 mercury mountaineer. how hard is it to replace the struts?

Check your fuses first, the highest fan setting runs off a big resistor so the slower speeds run off a fuse.

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