I just had an Exedy Twin installed and I was pleased with how it was all working... until I turned the heater on. With the fan set to 'off' there are no bad noises (aside from the rattly Exedy) but as soon as the fan is turned on to any speed, there is a groaning/grinding noise that comes from the engine bay. It is rather loud in the engine bay and it is coming from the front part of the motor on the passenger side (I am thinking the water pump). It goes off and on and sounds a lot like a solenoid for the heater as the fan speed does not change the noise and it did not appear to be occurring when the temp was on the 'blue' or cold side. It sounds pretty terrible and I need this figured out asap!

 

My friend (albeit an Accord) had a HORRIBLE noise when her fan was turned on, wound up being the A/C compressor. I can't seem to think of what else it could be. Especially in that area of the vehicle.

 

Do you happen to know if the water pump (or anything related to the radiator/ cooling system and heater) has a 'clutch' like mechanism that engages or disengages the pulley only when the heat is on? It seems it could be a loose pulley that grinds only when the wheel is slipping because the pump is engaged. When the wheel is disengaged, it is easy to spin and is no longer slipping. Does this sound like a possible culprit, a loose belt?

 

^^^^ The AC compressor has one.

 

Was your friend's issue related to heating despite being the AC compressor? I should look again but I swear it made no noise when the temp was set to cold.

 

^^^^ Check your PM.

 

Crisis averted, my brake ducting was rubbing against the compressor when it turned on for the defroster and AC.