Heater Takes A Long Time to Heat Up

[XCRN]

I am having an issue with my 93 525i where the heater does not really kick on until about 15 minuets of driving and makes defrosting the inside of the window a real PITA. The coolant temp gauge reaches to operating temp at a decent time well before I start feeling heat. I do not smell coolant in the cab but I am not ruling out the possibility of the heater core going bad. My only other idea is the auxiliary water pump is not working it's best. The thermostat was replaced before I bought the car but not sure what type. The blower motor works fine through the center vent, but I barely feel anything coming from the door vents so perhaps the cabin filter is also not helping the situation. Does anyone else have recommendations?

[cirrusblau]

Heater valves?

[chislern]

I would start with changing the cabin filter and go from there then look for an increase in air flow. The filter gets clogged easily. Cheers, George

[zubbie]

Heater valves?

My thought also. If the valves don't fully open, i.e. are stuck then not much heat will get transferred to the core. You could always bypass them temporarily to check.

[moroza]

I also place primary suspicion on sticking heater valves; it's a common problem at this age. They are spring-loaded to be normally open, and close intermittently via a pulse-width modulated 12V. You might try driving the car long enough for heat to work, then unplugging the 3-wire connector at the valve assembly. To be extra sure, turn the heater knobs to full-hot first, after heat starts working and before unplugging, then verify there's heat before shutting down. See how long it takes for heat to build up at the next cold start, and report back.

[XCRN]

I also place primary suspicion on sticking heater valves; it's a common problem at this age. They are spring-loaded to be normally open, and close intermittently via a pulse-width modulated 12V. You might try driving the car long enough for heat to work, then unplugging the 3-wire connector at the valve assembly. To be extra sure, turn the heater knobs to full-hot first, after heat starts working and before unplugging, then verify there's heat before shutting down. See how long it takes for heat to build up at the next cold start, and report back.

I will do that when I get back from down South this weekend. Thanks everyone for the tips!