Cleaning your mid-90s Seville’s evaporator coils of mold and other air-born particles
My 10 year old Seville had done many trips across the desert and into farm country during hot weather. What happened is that air-born particles including mold spores got into the evaporator coils of the A/C and consequently caused stale odors to come from the vents. To solve this, most shops charge $100 to $150 to clean and deodorize the evaporator coils. You can do this for much less, but I rate this maintenance as moderately difficult since it involves locating or fabricating a cover plate for the evaporator coil’s housing which must be applied after the job.
Supplies and tools:
Evaporator coil cleaner (e.g. Coil Cleen or equivalent)
CLEAN pressurized yard sprayer with a slight bend near the end of the tip
Good lighting – flood lamp with clamp to attach to hood latch
Drain pan – either oil pan or dish pan (plastic)
Evaporator housing cover plate – if you can get one by GM or make one. (I checked with 3 Cadillac dealerships and no one knew of a replacement cover for this area once cut out. I’m sure there must be something manufactured for this purpose but I could not find one.)
Note: If you cannot locate a cover or make a durable cover of say metal beforehand, DO NOT attempt this job.
3 sheet metal screws to secure the cover plate
Place an oil drain pan or plastic dish pan under the weep hole under the car for the A/C’s condensate discharge (under evap coils behind RF tire and just under strut).
The cover plate (purchased or fabricated) must be large enough to cover the area BEYOND the cut out inclusive of the semicircular “ears” and have this ready before you begin! There is a rectangular embossed area between the blower motor and the evap coils that says “Cut here for service”. Notice that it’s an odd shape with 3 small semi-circles around it. This material is a soft plastic and directly beneath it is the metal evaporator housing. Cut the soft plastic by using a utility knife and follow the edge of the opening below the plastic. Be careful not to let the plastic cut-out fall into the opening by holding an edge of it with a pliers. Pull the cutout away from the opening and discard. Now you will notice that the semicircles are above pre-drilled holes for sheet metal screws. These are the locations that you will drill into your slightly oversized cover plate to re-secure the opening. I say this because the A/C is not usable again until the cover is applied.
Pour the contents of your coil cleaner into the yard sprayer and compress. With flood lighting, you should be able to see the evap coils which are in a geometric matrix.
Apply the coil cleaner sprayed as directly into the matrix as possible. Go up and down the matrix approximately 8 to 9 inches deep and across the width as far as you can reach applying the cleaner. When done, carefully depressurize the sprayer and pour the leftovers back into the original container. The coils should be allowed to soak for about 10 minutes.
While coils are soaking, thoroughly rinse your sprayer, fill it halfway with water, pressurize and spray the remaining chemical in the tubing into a drain until clear water comes out. After 10 minutes, you can spray clean water with your pressurized yard sprayer generously into the coils again – be sure to get into all areas that you applied chemical to. You should notice quite a bit of drainage from your weep hole beneath. Be sure your drain pan catches it as spillage could stain concrete. Thoroughly rinse out your evap coils. The drainage will go on for awhile – up to ½ hour.
Bolt on your fabricated cover with your 3 sheet metal screws.
Start the car and turn the A/C to max (but not recirculation). More weeping will happen – this is normal. There may be a slight chemical odor for 10 minutes. Optional: You can spray a deodorizer onto the coils such as Febreeze or Lysol Fresh Linen, You decide if you want to, remove the cover plate and spray a deodorizer over the coils. Most of the weeping should be done within a half hour.
Dispose of the drain pan contents properly. Ahhh – fresh air from the vents again!