ive been working on the a/c in my 91 firebird. its cooling great but the blower isn't blowing very hard. I pulled the motor thinking it was clogged with leaves but it wasn't. I replaced the motor thinking it was worn out. there was a marginal improvement in flow but nothing like I expected. am I expecting to much out of a 27 year old system? it doesn't seem correct. do your ac blowers blow hard? what should I check next?

1-not clogged
2-motor is new
3- I was told to remove the kick panel and check for air leaks ( not exactly sure what im checking
4-there is a door right behind the blower motor. where is that supposed to go?

 

The "motor" (I'm guessing you're really referring to the "squirrel cage") rarely gets clogged.

Rather, the surface of the evaporator does. All the schmutz that comes in - leaves, dog hair, bird plop, grass, dead bugs, whatever - ends up stuck there. THAT'S what needs to be cleaned. You might be surprised what you find laying in there when you pull it out ot otherwise expose it to the light of day.

The door right behind the blower motor, IIRC, is the recirculate one. It selects between the motor drawing in air from the outside world, and drawing it from above the passenger's feet. Not sure how that's marked on your particular control head, but on most of these cars, it's called "Max A/C".

 

my understanding to check for the "clog" was to remove the blower motor and cage and clean out the area behind it. where is the evaporator located on thirdgens? when I set the dial to max a/c that door opens and pulls outside air in?

 

located the evaporator. looks like its 6 bolts to remove the top cover. can I remove the evaporator coil without losing my Freon? or should I wash it in place?

 

You can wash it in place but I think you'll want to do more than that when you see it.

Yes the refrigerant will all escape if you disconnect the lines. However, THE ENTIRE system - compressor, condenser, lines, accumulator, and evaporator - will lift right out as an assembly if you do it right. Look carefully and you'll see what I mean. You can probably free it up enough to get the evap out far enough to do a good job on it.

 

In addition to what has been said

A few other things to check.
There are "doors" that are controlled by vacuum that direct the air to vents. With no vacuum the only vent that is open is the defrost.
The door actuators can break and get stuck in a closed position.
There is a vacuum selector valve on the back of the control panel that is known to break, if it does then the vacuum leaks and the mode selection doesn't work right, causing for weak airflow.
The foam rubber that seals the air ducts has likely turned to dust or at least turned loose and is leaking. (specifically at the duct to vent connector)
The air seal on the top of the AC box outside the car is likely leaking.
The air seal for the condenser to the box is likely leaking.

FWIW my condenser had a "filter screen" on it.

The other thing to check is grounds. If for instance your windows are really slow at going up/down and causes your lights to dim you need to clean and or replace the engine/frame ground straps and the ground cable from the battery to the block.

 

FWIW for the vacuum selector there is a 3d model you can print of the part to fix it https://www.thingiverse.com/thing:3331481 though I just used a screw/nut and loctite.

 

Incidentally, the evap housing in my 83 eventually disintegrated above the exh manifold; the material just turned to dust and crumbled. I found a hole about 3" in dia there... invisible with the engine in place. Which of course meant that my blower was working its butt off blowing air onto the #8 header tube instead of into my car.

You'll be able to see that place from the inside with the evap out.

I fixed mine with fiberglass.

 

I have all the bolts out of the evaporator coil housing. its free but I cant get it out. is there a secret here? its hitting everything and its recessed under the lip of the fire wall. the manual doesn't mention how to remove it.

 

The whole housing should come out. 4 bolts / nuts across the top accessible from under the hood, 3 across the bottom accessible from the interior, all 10mm hex IIRC. I had mine out that way, don't recall it being a problem, but I had headers at the time. Might have to take out the exh manifold to get clearance if you still have those.

 

If you are referring to the top of the housing, my 90 had a seal between the housing top and firewall. the seal was sticky, so that could be causing it not to move. I also had to loosen the wire harness to get more room to maneuver. once both of those were done it lifted right out. I also had accumulator out of the way, making it even easier.

 

How did you get the top cover for the evaporator back on? I'm trying to get mine back in place and it won't slide across the top of the evaporator because of the ridges on it. There's just enough space to slide the top in but it won't move because of those ridges. I was thinking about bending some very thin sheet metal to cover the top of the evaporator so the cover will slide across it back into place.

 

They're ALOT eeeeeezyer to put back together if the whole thing is loose from the car.

Clean up all the old gook between the housing and the firewall; and use windshield sealer to put it back. Works WAY better than whatever the factory used back in the day.