318i Heat Only works when I'm on the highway

[cooliesupreme]

Hi, I have a 95' 318i.

The heat used to work perfectly. Then one day I noticed it only blows cool air, unless I'm driving fast (like on the highway). When I'm driving fast, warm air comes out, but still not as HOT as it use to be.

Once I get off the highway, he air gradually cools and stays cool.

Any suggestions?


Thanks,
C

[rjjarvis]

Start by doing something cheap and easy: replace the thermostat.

[cooliesupreme]

I'm wondering why replacing the thermostat would help, since the heat works when I drive at high speeds?


Thanks,
CP

[Bimrpwr]

i doubt it is the t-stat.

Could be the heater control valve.

Also check your coolant level and try to bleed some air out of the system

Also what does the car do when you have the HVAC unit set to recycle air instead of fresh air?

[paidnfull]

Mine does the exact same thing but i know its due to low coolant. I have a a loose clamp on the lower hose and coolant leakes out all the time. When it gets to a really low point, thats when the above mentioned problems occur

[Bimrpwr]

Mine does the exact same thing but i know its due to low coolant. I have a a loose clamp on the lower hose and coolant leakes out all the time. When it gets to a really low point, thats when the above mentioned problems occur

can you make your sig pic smaller please...

[paidnfull]

can you make your sig pic smaller please...

If you make me one i'll gladly use it

[Bimrpwr]

If you make me one i'll gladly use it

well open up a paint program and resize it...

Sooner or later the Mods will delete it for you..

[campaiar]

Its the thermostat. They usually fail open and the coolant flows continuously from the radiator to the engine, preventing any heat from being retained.

If you can't get to it right away, slip cardboard between the radiator and the grill covering about half of the radiator up. This will keep you warmer. Keep your eyes on the temperature gauge though. If the needle wanders past half, stop and remove the cardboard.

[cooliesupreme]

Well, my water pump went, and I had to replace it along with the thermostat. Now I have more than enough heat.

Thanks for the suggestions.