My '91 AC blower doesn't seem to blow as strong as it should. I've got the electronic ( C68 I think ) Auto AC.

The fan blows, and there is a difference in the fan speeds when I hit the fan speed button up or down, but even on 10 it doesn't seem to blow like it should.

Air blows cold, just doesn't seem strong enouph.

Any Ideas.

All the vents, defroster, heat vents work as they should.

 

Sounds like you have a common problem. If you check your defroster vent, you will probably feel some air coming out there. If you do, you defroster vent door is not closing all the way. The only way to fix this is to tear into the dash and replace the vent assembly. This is what a vette mechanic told me, I have not done this yet. Waiting to do the CD repair and other in dash repairs at the same time.

 

Thanks Randy, I'll check the defroster vent when I get home !

 

Defroster and heat vents should produce a small amount of cool air - it was designed this way. Easier to troubleshoot an airflow problem by jumpering the blower motor to the battery. If the airflow is stronger, then something is up with the blower electrical signal. If it's the same, the duct work is leaking or air flow is restricted - usually because the evaporator is plugged up.

 

Check your vaccuum lines... before you the dash apart...

My 84 had the same problem... broken vacuum line and problem fixed... check that first...

 

hey, some great comments, I'll check them all.

Thanks guys

 

 

My problem was a weak blower fan motor.I replaced it with a new one and it began to blow alot harder.It seems over time they spin weak.

 

Here you find pic from what my evaporator looked like from my 1990, when it has same symptoms.
http://www.hyke.fi/moisio/ac.jpg

The red circle shows the area where there was still a little flow through.
Enywhere else it was totally blocked.

 

Yesterday I plugged the HVAC vacuum line directly onto the intake bypassing the check valve and the ac would not blow thru the vents, only the defroster and heater vents, when I unplugged it the hose from the manifold, the air came out of the vents, any ideas.

 

How hard is it to get to the evaporator?

 

The more you remove (including the right header & head - but it isn't necessary) the easier the job. Basically, put it on jackstands and then remove the right wheel and inner fender, blower motor, windshield wiper fluid container and pump, EST module (if equipped), and anything else in the way. Remove all the bolts (there are several that will have to be gotten from underneath the car), split the case and take off whatever side comes off the easiest (for my '89, the side closest to the engine had to come off first, but I was replacing the Evaporator). Just be sure to support the Evaporator so it doesn't fall and kink the lines.

Be sure to reseal the case, otherwise water will get into it and overwhelm the weep hole soaking the carpet. I use window ribbon sealer which is readily molded and really sticks (remove any excess with a razor blade and denatured alcohol). Be sure to use plenty around the lines too or you'll have some of the cool air blowing into the engine compartment. After you get it running again, feel around for any air leaks and plug up any that you find.

Before you start this, you may want to have an a/c shop stick an electronic sniffer in your vents. If it's leaking, you will want to replace it and you might be able to work a deal with the shop to suck out your gas, leave and do the labor yourself, then return to have a vacuum pulled and the gas put back in.

 

I still think its the blower motor.You can try changing the relay first.If that doesnt fix it,maybe a new blower fan.As I said earlier,I had the same problem and the number 10 setting didnt feel strong.With a new fan,it was blowing hard in my face,as it did when I first bought the car.
Over the years the fan power felt weaker over time.

I also agree with checking any possible obstructions or blockage.That may help too.
Good Luck!