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Sorry if Im beating a dead horse here but Ive had my 1998 C5 for 3 years and it has climate control. Even though the fan speed indicates the blower is going full speed, on the control module, the volume of air feels more like medium rather than high speed. My son has a 2001 and his high speed is at least twice the volume of air than my high speed is. I have replaced the blower motor and the resisstor with no luck.
So yesterday during my research I found out there is a 1st and 2nd generation of blower motors and there is a different blower motor for the manual hvac system and for the climate control system. I have always suspected that my sons blower motor is spinning way more rpm's than my blower motor.
So I want to know if there is a difference in speeds between all these different blower motors and how can I find out what the different speeds are. My idea is to hopefully install the blower motor with the most rpm's.
Last edited by chevyvette98!; Jan 13, 2026 at 11:48 AM.
There is no service information regarding the blower motor "speeds"...before going any further and shotgunning more parts I'd make sure the blower motor is receiving FULL power and ground...if you are not familiar with this electrical testing seek out an auto electric shop in your area.
Should the blower motor be recieving 12+ volts when the blower speed indicator on the control head is on the highest setting?
Also the schematic lookslike it is for a Manual control, where as i have the climate control .
Wouldnt it be easy enough to use a multi meter to checj the voltage at the blower motor? and also as I decrease or increase the voltage to the blower motor, I could also see that at the meter? But then would I not be checking the amp to the motor . It has been suggested to me to use an old headlamp, because as I increase and decrease the voltage to the blower motor the lamp would get brighter and dimmer.
Last edited by chevyvette98!; Jan 13, 2026 at 12:48 PM.
Should the blower motor be recieving 12+ volts when the blower speed indicator on the control head is on the highest setting?
At the highest speed all of the resistors are being bypassed so you should be seeing somewhere around 10-14 volts...removing the connector and just checking "open circuit voltage" for proper voltage is meaningless !!
While not an expert on the HVAC electrics yet, I will note two things I’ve seen make significant differences in air volume.
First, if manifold vacuum is lower than nominal it can keep the defroster diverter from opening fully, impeding air flow. On my ‘99 I was getting more air from the defroster than anticipated. Turned out my vacuum canister was cracked.
Second, fresh air flows about half the air of recirculating. Makes sense with recirculating moving around the air within the cabin and fresh adding more air into a somewhat sealed cabin.
Im going to assume the OP knows about the recirculate button. On my car, and most GM cars, pushing that button greatly increases the fan speed, even if you're fan is already on high. Just sayin'......
Yes i discovered that about a year ago. I use it all the time for heat and AC. End with that on, the powser of the blown air comong through the vents seems like it is only 50% of what my son ( 2001 C5 ) car puts out.
HVAC Blower issues
