My heater is acting retarded. When the car is completely warmed up and I turn on the heater, it will heat up for a good 30 sec. and then blow cool air. It keeps heating up and cooling down as I drive down the road. What could possibly cause this?

 

How's your thermostat?

 

wtf?! thats bugged out.

 

I dont know, is the thermostat relative to what temp the air is on the heater?

 

It's probably stuck open.

 

min's doing the smae thing if i rev it, the heater blows hot air if i idle its cold... help!!

 

if your thermostat is stuck open, you will see the temp drop as you drive faster down the street/highway and go back up when not moving. What you are describing (both of you) sounds like a clogged/partially clogged heater core that only allows circulation when the water pump spins faster and puts more pressure on the system. Sounds like time for a serious system flush.

 

Another thing to check is coolant level in the radiator, if the system is low it can cause erratic heating. i personally experienced this on a vehicle I used to own. no guarantees, but that was my prob and definitely worth a check, check the radiatoras well, not just the dummy tank. If not, I second the motion to have the system flushed, clogged heater cores suck!

 

Low coolant level is a big reason for this behaviour (cold air from heater @ idle)

 

Low coolant level

Bad thermostat

Plugged heater core

Malfunctioning vent control

Those are just a few that came to mind, there is a very good preliminary checklist flow-chart thingy for diagnosing insufficient heating in the FSM

 

Is tis for real - - yu'v been mbr for 2 years and don't know how this works. Sorry for the flame - but get real