ian1035nr

Howdy, everyone

I’ve got a problem with the airflow through my 2002 Chevrolet Malibu LS.

There’s plenty of air coming through the vents when the vehicle is first started, then it gradually slows to a trickle as the car is driven.

The air isn’t coming out of any vents other than what I have selected, the blower motor still sounds like it’s running at the same speed even as the airflow wanes. It isn’t any better switching to recirculate mode, which would bypass any potential clogs in the outside air intake.

Things I’ve done so far:

1. Replaced the blower motor with a brand new, genuine GM replacement.

2. Used compressed air to blow out the vents and the cavity surrounding the blower motor.

And that’s where I’m at. The fan always returns to normal after the it’s been switched off for bit. So it’s almost like something is overheating. But the fan is still running at the same speed… So I’m stumped

tech2

auto hvac or manual? if auto make sure you are in manual mode and see if the problem is gone.

ian1035nr

It’s manual, I don’t think automatic air was ever offered in these cheap little things.

I pulled be resistor and although there’s no markings on it; I believe it’s a replacement from Standard Motor Products’ cheap T series. I’m going to go grab an AC Delco blower resistor from the dealer and see if that does anything.

tech2

auto is an option on high trim levels.

make sure the cabin filter is not plugged...this will restrict airflow

ian1035nr

I have the highest trim level of Malibu for ‘02 with every optional feature installed. And the manual makes no mention of auto air. I think you’re confusing my model for either an Impala or a newer generation of Malibu.

There also isn’t a cabin air filter. I had my suspicions while working on it and confirmed it with Google and the dealer.

But even if there was, the air would be restricted at all times and not only after the system is running for a while.

tech2

did not see this was an 2002

tech2

does the airflow c hange temp or door mode positon when the problem occurs. the system uses vacuum for temp and mode door positons....this would change when driving as vac drops at speed. there are check valves and vac reservoirs designed to prevent this but maybe there is a leak. a recirc door change will change airflow volume

if you think its a voltage problem to the blower....measure and monitor voltage to the blower motor purple wire during a test drive....if the voltage drops...its an electrical problem.

ian1035nr

No, the temperature and position doesn’t change, as indicated in the 1st post. Once I have it set to certain position, it stays there.

I think I figured it out, anyway. It seems the evap core is frosting up. The problem only occurs after the A/C has been running and goes away if I switch the heater on, close up the vents and let the trapped hot air defrost it. The orifice tube and drain aren’t plugged in any way so the core itself is either obstructed by something that’s retaining moisture or there’s a refrigerant leak. I’ll have it tested at some point and go from there.

In the meantime I’ve sprayed a cleaning mixture in through the outside air intake and ran the heater with all the vents plugged up for a while. There was definitely a faint, vinegar smell when first starting the car, so there was some mold in there that had to be dealt with regardless.

tech2

the low pressure switch or wiring may be faulty....that is the trigger to cycle the compressor off.
a leak would not freeze the evaporator but an over charge would...its floods the evapaorator...it causes the state change to happen after the evaporator.

ian1035nr

The problem isn’t that the air isn’t cold

The problem is that there isn’t much air of any temperature moving through the vents.