what's wrong with my car's heater?

danger boy

the heat in my car isn't working. it's blowing cold air.... so not sure what the problem is.. it's got plenty of coolant.. maybe the water pump is going out>? how would I be able to tell if the water pump is failing?

DaveHo

If the coolant isn't low your heater core may be plugged. When's the last time the system was flushed? Or a bad thermostat not allowing the coolant to get up to temp. What's the temp gauge say? Could also be a vac leak preventing a damper from directing air flow over the heater core.

-Dave

silvertuner

well, there are a number of things it could be. please start out by telling us what vehicle it is.

it could be anything from a bad body control module to a plugged coolant line and anything in between, around, or not related to those lol

danger boy

ooo.. ok.. 1997 Mazda 626 with 138K miles

car warms to normal temps according to the temp guage... and blows cold air.. once I'm zoom zooming down the highway though.. heat comes out. I was getting a check engine light for about a year.. now that's gone. and i'm getting cold air. LOL

flushed the system last Nov.. so about 3 month's ago. I hope it's not the heater core.. ugh!

gdb

Did you spill anything sticky down the vents? That caused a "flap" to stick in my truck years ago. It wouldn't pop open to direct airflow until the sticky soda warmed up enough to release it, then, everything worked fine until the next cold start up.:biggrin:

Jstas

If it lit a light, there's a code. Get it read at like AutoZone and find out what it is. We can go from there.

As far as heat, probably a clogged heater core. I had to replace the heater core in my 98 Taurus at about the same mileage.

The other thing could be the blend door. However, if you had a check engine light on, it was likely due to a vacuum leak. Know what makes a blend door move? Vacuum. If the blend door is jammed up or the actuator is broken, it'll leak and it can cause a check engine light.

One thing though, is the HVAC fan working?

exalted512

Checked the fuses?

Its 81*, what do you need a heater for? Put it off til next December
-Cody

danger boy

all good ideas.. i will have it checked out.. vacuum leak.. sounds possible.. because it didn't pass the state emissions test last year because of the check engine light on.. got it fixed.. then the engine light came on again.. but the car runs fine, except no heat at slow speeds.

i'll park it till next week.. we're suppose to be at 0 degrees the next few nights.

ben62670

Sounds like you have an air pocket in your cooling system. Some engines have bleeders to remove the air. I had issues with mine. I had to park on a steep incline to fill the running engine with coolant or I would get an air pocket.
Good luck.
Ben

mhardy6647

thermostat stuck open?

Zeros

I had the same problem today. I added a bunch of antifreeze to the reservoir and it's all good now. Apparently it was quite low. I'd try that first since it's the cheapest fix.

danger boy

Zeros wrote: »

I had the same problem today. I added a bunch of antifreeze to the reservoir and it's all good now. Apparently it was quite low. I'd try that first since it's the cheapest fix.

Oh good idea.. i didin't add any coolant to the reservior.. and I think it's low... the level in the radiator is fine though. i know that for sure.

ben62670

If your reservoir is low then you will suck air into your system when it cools down. Air pocket prevents flow. When you are moving along at a good clip the coolant is pushed past the air pocket. Then you have heat. Been there done that. Near free fix.

danger boy

ben62670 wrote: »

If your reservoir is low then you will suck air into your system when it cools down. Air pocket prevents flow. When you are moving along at a good clip the coolant is pushed past the air pocket. Then you have heat. Been there done that. Near free fix.

is there a mod for that? :biggrin: :rolleyes:

ben62670

Ask CL35. I think it involves a 2uf cap

mrbigbluelight

Also, underneath the hood back towards the fire panel (left side as you're facing the car) : there should be a vacuum line going to an acuator. Vacuum line may have come loose, developed a hole (heat induced), or the mechanical arm that opens the heater core flap is loose from the actuator.

I'm charging $75 an hour for these guesses, btw. So far .... you're down $12.75.
Worth every penny though.

Regalscenter7

goto advance if you can (i work there hahaa)
sounds like it could be a water pump.
because you said once you get going it gets warm. but if your getting a code it might be a thermistat, ive checked codes for people before and it came up as coolant temp below threshold that would indicate a bad thermistat (stuck open) i would grab a new one from advance auto they cost around $7 or $9.99 for a lifetime one

JimKellyfan

As long as you are full on antifreeze, first check to find heater hoses with car off and if you can safely grab them while car is running or not. Anyway, with car running and heat on full blast, grab each heater hose. They should both be warm or hot to the touch with heater running. If not able to check while running, check after fully warmed up and heat on full blast with car off.