91 TA Vert.....
It's hot here in central Texas, and although the morning drive is pleasant with the top down, the drive home from work with the AC on just sucks. This is still an R12 system, but the fan is not strong enough, even on "max." I've checked the entire system I/A/W the troubleshooting tree, and everything works as it should except for a fan that is seemingly weak. (My 94 TA's fan will blow you out of the car, so to speak.) The fan is new. replaced about a year ago. OEM Delco.

My gut feeling is that the evaporator is clogged with debris, and has never been cleaned, so I've resolved to cleaning it.
I've looked on YT and cannot find a definitive answer to: Can I just remove the top part of the "module," (#17,) (shown in blue,) without compromising the system? If I look in the photo from the IPB (attached,) and on the car It appears that the top part can be removed without removing the accumulator, as there is a slot that slides over the fittings and line.
True or not?

Thanks for the help and any insight.

Jeff

 

I don't know how to clean the evaporator but I have a few other things that might help. Do you have dual fans? I added dual fans and it helped quite a bit. Also, the foam inside the evaporator box gets old and brittle, allowing hot air to flow past the evaporator. I know people have replaced that foam and had better performance.

 

Hey badtenant.....Thanks for responding.

I'm a little puzzled as to why radiator fans would have anything to do with HVAC fan power....however, it's a TA, so I do have dual fans....It also has a 160 degree thermostat and a chip, that was installed long before I purchased the car. Going home the other day @ 107 degrees F, A/C on max, car @ 60 MPH, I never saw more than about 175 degrees F.
I, however an going to figure out how to clean the evaporator, as I do believe there's something going on...

Jeff

 

Checkout 36:10 in the video....Maybe that gives you some hope that it can be done without evaluation of the system.

I mentioned the fans becuase for me the dual fans helped move more air over the condenser lowering the vent temperature. I too have wondered how to increase the blower speed but found that making sure a/c is working correctly helps tremendously.

Things that helped me get better A/C performance:

Tinted Windows
T-Top Shades
Parallel Flow Condensor
Sanden Style Compressor
Ford Orfice Tube
Dual Fans

 

I also forgot to mention that I covered the floor with some closed-cell heat shield material. The heat radiating from my transmission tunnel and under the seats was crazy. The carpet actually feels cool now after this stuff.

 

both your thoughts were perfect! Thank you!
Actually on my way to get the car now,( i keep it in a steel building i own a mile from my house eith my other toys,) and have a look at the evap. Not ready to change the system over yet, but at some point in time i will. I have an additional disadvantage because its a vert, and no way to insulate over my head....however, thr PO gave me some sort of cover to use when parked, and he never said what it was for.

Thanks again!

Jeff

 

I'm going to revive this thread because I think this is something I need to do as well. My compressor is leaking at the moment so no a/c, but I know a dirty evaporator can also cause weak heat as well because the airflow is restricted. I'm old enough to remember how the air blew in these cars when they were new, and mine is nothing close to that.

Ive seen modern cars ran without cabin filters and get clogged, so I'm pretty sure all of the older ones end up the same way. I had to make a special tool from a nozzle and pex pipe to clean the evap in my Nissan van because the previous owner ran it with no filter.

 

I forgot to post this back in the fall when I finished, but I've totally restored airflow. Here's how I did it and how I cleaned the evaporator. I also removed all the ducts from behind the dash, cleaned them out and resealed them where needed. (Photos may not be in order.)

A Much Needed Modification
Third Gen Evaporator Airbox.
I was having a problem with airflow thru the interior ducting in my 91 TA. I had suspicions that it was a clogged Evaporator Core, rather than the blower, as I replaced it about a year ago with an OEM unit. It turns out I was right. I suspected the Evaporator had never been cleaned, even though the maintenance on this car was "top-notch" before I purchased it. The Evaporator is easily overlooked unless it leaks.
The Evaporator core was extremely dirty, clogged with debris and old foam, as was the “condensate screening” on the output side of the Evaporator core. As of this writing I also cleaned out and resealed the ducting behind the dash. Airflow has returned post cleaning.
The problem with periodic cleaning of the Evaporator is that in order to do it easily, in reality, you have to evacuate the A/C system and remove the Receiver/Dryer, so that the upper part of the Airbox can be removed without damage to it and other components in the area. The way GM designed it, the entire Airbox has to be unfastened from the firewall to easily access the Evaporator.
I was having none of that. I convinced myself that I could remove the upper Airbox/Evaporator Cover without breaking into the system or removing the Receiver/Dryer. The problem is that the rear flange of the top of the Airbox is actually under the lip of the Cowl and the forward end surrounds the Receiver/Dryer connections, so you’re screwed. I attempted to spread the forward end out enough to clear the tubing, and although I got it off and was able to do the Evaporator cleaning, I cracked it in two places fore and aft. I stop-drilled the cracks, reinstalled it, and applied “four-season” tape over the top, convincing myself I was going to do better.
I purchased another top cover from an Ebay seller, and planned my modification. I decided to cut the cover in half longitudinally, for ease of future removal.
Materials required:
Piece of .060 Kydex sheet, cut to 2.5” X 7.75”. (Available Amazon and other places.)
Quantity 12 “Christmas tree” small plastic automotive “push fasteners.” (See photos, Amazon.)
VHB tape
Tools required:
Shear or utility knife
Drill Motor
#40 Drill
#30 Drill
Unibit
#40 and #30 Clecos and Cleco pliers
Dremel with cut-off wheel
File
Clamps
“Four Season” tape
Process:

• After receiving the replacement top cover, although it was what I expected, the plastic was kind of whitish (probably from age and/or sunlight,) than the one in my car. I washed it with some purple power and a toothbrush, then, when dry, took a heat gun and restored the plastic “back to black.”
• Using my shear, I cut a piece of Kydex to the proper dimension. I chose the 2.5” width so it would fit inside the two vertical stiffeners on the firewall flange. (circled in red.)
• After cutting the Kydex patch to size, I marked the location, and using the Unibit, drilled an 11/16” hole to go around what is either a “boss” as a result of the plastic molding process, or an attach point for an accessory not utilized on the Firebird. (circled in yellow.)
• I laid out for 6 fasteners on each side, (overkill, I know,) approximately 3/8” inboard of the edges of the Kydex patch.
• Since the top is curved, I applied VHB tape to one side of the Kydex, and taped it into place.
• Then I drilled a #40 hole on each end, and installed the Cleco fasteners.
• Then I “rolled” the Kydex patch around the top of the box cover, used 2 small Vise Grip clamps, and drilled 2 holes fore and aft on the other side.
• Drilled the remaining 10 holes to #40, installing Clecos as I went along.
• Once all the holes were drilled, I opened all the holes up to the final #30 size, and then removed the Kydex patch and de-burred all the holes.
• Note: The “Kydex patch” and airbox top should be completely fitted and drilled prior to cutting the Airbox in half to assure proper installation.
• Using the Dremel and small cut-off wheel, I cut the Airbox top in half and deburred it.
• My original Airbox top has some kind of molded white thin foam glued on the “screen side/output side” of the cover that the replacement did not. I was able to transfer it and glue it into the replacement top.
• I used black butyl seam tape on the firewall and mating surface (top to bottom) flanges, (with a “dry release” agent) and installed the patch with the push fasteners.
• Applied a small bead of “four season” tape to the forward edge.
• Looks really good, and although not “factory or original” it will be a lot easier to service in the future.
• 
  
  
  
  
  
  
  

 

wow. That's impressive!

What about the hole on the top left of the cover? Can you see the coil that way? I have a gun that I made from a hose nozzle, and it has a capped pex pipe about 6" long with a hole drilled in the side. I made it for my Nissan van so that I could put it in the filter slot and blast a stream of water sideways into the coil. It worked for that situation.

 

Are you talking about the large hole where I believe what's called the "thermistor" goes?
You can see in there, however, on that side of the evaporator (which is the output side,) there is a piece of screening, (just like window screen,) that traps water droplets and prevents them from being carried with the forced air and coming thru your dash vents. Also, without removing the cover, you cannot get the debris out from behind the screen, below the evaporator , and adequately wash the evaporator "backwards."

 

ah. I see.

I suppose it wouldn't be a big deal for me to remove my dryer since it's not charged anyways.