Weak ventilation air flow

I have 91 lumina and the air flow coming from any of the vents in any of the climate function modes seems very weak. I would compare it to a low or medium speed on any other vehicle I've ever owned or worked on. Every function works and the air teperatrure coming out is very cold in the summer and hot in the winter, but there is such low air flow that it takes a long time to warm or cool down the inside of the car. On some hot days, it never seems to be quite enough air flow to cool down the car completely, so it is necessary to use max AC on full blower the whole time. I have disasssembled/cleaned the front cowl intake all the way to directly view the blower and it is running properly. I have just disassembled the under dash and verified all the air doors are opening/closing properly. All the fan speeds work and the blower sounds like its moving alot of air. I have not removed all the duct work, but see no obstructions from what I have removed- which is considerabe.

Is this typical for this model and year. I have noticed a few other posting for this condition, but I am way past trying the basic replies suggested. Any ideas on defects or even upgrades to the blower motor or wheel fan design- to move more air? It seems the air tubes going to the dash vents are unusally small in size- perhaps to increase the air speed as it moves through them- maybe this overly restricts the volume needed for the car interior?

my guess is that the evap core may be plugged with mold and mildew, and is not allowing enough outside air into the vehicle. This is a common problem with older air conditioned cars. They make an aerosol cleaner available at most auto parts stores

YES! Had that problem with an old Caprice wagon, just never gave it much thought. when the evap went bad and leaked, I removed it to find it a solid wall of wet slime, with no air flow.

Thanks Richtazz & Jeffcoslacker. Wtih furhter disassembly I gained some access to the inlet side of the evaporator. I was plugged with a layer of dirt and fuzz and whatever else. I used a soft bristle brushh to reach up and get as much off as possible. Then I blew through it form the opposite side using an air hose and extension wand. I did not want to disconnect the system(s), heat and cold unless necessary.

As a result, there is a huge difference and it is quite acceptable now. Thanks again for the idea!!

gotta love it when the fix doesn't cost you anything but a little time. Glad we could help you out.

I have the same car and the same problem. Would you mind giving me some detail on where the evap core is and what it looks like. thanks. Sorry about the double post, got lots of things that need taking care of.

The Evap core is part of the AC system. It is the small "cold radiator" component up under the dashboard. Air comes through it first and is cooled then into the car. Cold and condensation make it attract more dirt. It looks very similar to the heater core- also under the dash. Both are very close to each other and packed into the ventilation system. They can both be accessed by removing 3-4 dash/ventilation panels. Be prepared to lay upside-down for awhile.

However, you cannot completely remove them without opening the heating/coolant system and the AC system. You risk creating future "leaks" in either system if not careful, plus they will need to be charged/refilled once reconnected. This is why I decided to loosen the heater and evap cores to pull them out a little as much as possible (and it ain't much) then reach up behind the Evap core to brush it off.

The heater core right is in front of the evap core, so once you locate the heater core- the Evap core is in the next panel behind it almost up against the inside firewall. Good Luck!!

Thanks Meisermind! I tore everything down to the heater/ evap core, but when I pulled off the cover I noticed that there was some yellow greasy liquid on the bottom (where there is a drain hole). Parts of the heater core and surrounds were noticable damp with the same greasy yellow stuff. Does anyone have any idea what this could be? I am somewhat sceptical about it being coolant as is is yellow and greasy and not green and watery. Could it be air conditioning related?

Every post is a little more helpful. Thank-you all. I will carry on today and report tonight on what I have accomplished. I can't seem to see how to get the panel off behind the first core I have uncovered.

Thanks Meisermind! I tore everything down to the heater/ evap core, but when I pulled off the cover I noticed that there was some yellow greasy liquid on the bottom (where there is a drain hole). Parts of the heater core and surrounds were noticable damp with the same greasy yellow stuff. Does anyone have any idea what this could be? I am somewhat sceptical about it being coolant as is is yellow and greasy and not green and watery. Could it be air conditioning related?

It is not uncommon to find all kinds of slimy mold and algae growth if the core drain is blocked or there is standing water in the box. I think that's what you're seeing. Sometimes it is a comination of mold, pollen, dust, so be careful not to expose yourself to it much, if possible.

It would be a good idea for all of you messing with this system to dry it as much as possible, then spray with a spray made for cleaning/disinfecting the cores, or at least some Lysol or something, because now that you have disturbed it, you are gonna be blowing it in your face through the vents, once you get it back together. Fogging the ducts with it would be a good idea too. Lots of nasty stuff lives in there, and is usually not a problem unless disturbed, then it starts coming out with the vent air. Can be a problem for people with allergies or respiratory problems.

CalgaryLumina,
Your damp stuff could just be accumulated moisture and dirt over time. It could be a very slow leaky heater core, or possibly a very slow leaky evap core. An oily substance could leak from the AC system, but in short order your AC wouldn't turn on because of low pressure (a leak). I would just disinfect/clean off all parts and then run the vehicle and observe for leaks. The evap core should normally drip condensation water after a while depending on weather & humidity. Thats why the drain tube going through the fire wall. Make sure the drain tube is connected, intact, unclogged, and then the tube must make a 90-degree turn downward after going through the firewall. I had to temporarily disconnect mine when cleaning the evap core. It was difficult to reconnect (took 2 beers and some cursing) and it must aim down when done.

I opted not to buy and spray the evap cleaner beacause I was afraid it would clog up the evap core even more with the very limited access I had. I feel I was able to get more dry fuzz to brush off and fall to the floor this way. I did not think I would be able to get the cleaner/foam and dirt off once applied. It appears a good product but, I think in the case of this car- the evap core almost needs to be disconnected and removed to use it properly. Perhaps wear a mask if you have weak-lung syndrome.

I actually purchased an air compressor to try to blow the evaporator core out. It was too greasy. I then went to a radiator shop and he showed me a core he had that was the same as mine. He said there is no way you are going to get it clean enough to get air through it. I now need a new core which is $192.00 Canadian. I am about four bolts away from removing the evaporator core, I have had to undo the motor mounts and tip the motor forward. I will try to remove the core tomorrow. I will let you know how this all turns out.

The back of my evap core was also covered with oil from a leak in the air conditioning system somewhere above the core. The front was clean so I decided to try to use some engine degeaser and acetone to clean the back. That was a mistake, it was a dirty smelly job, I'm not sure if it helped, and now my car smells like solvent. Hopefully driving around with the heater on and the windows open for a few days will fix the solvent smell.

Sometimes the "easy" rode turns out harder... I think removing the evap core it definitely the way to go when it has any kind of oil on it.

Going to wait until winter though and see if my cleaning job did and good, if not I'll take it to a shop and get them to take the evap core out. Not going to bother replacing it and getting the AC running again, I've been told that's a $1000 job and I don't really care about AC that much.

Can anyone tell me where the release valve is for the air conditioner? I need to release all pressure and drain the fluid before I can remove the evaporator core.

Well guys my problem is solved. I decided to take it to the radiator shop and see what it would cost for them to fix it. I left it all apart. They charged me $85.00 Canadian to clean the evaporator core. They didn't put it back together for that price but hey I took it apart and can put it back together for the money I have saved.

glad that fixed it.

Did you pull the core out of the car, or was it still attached?

It was still attached. I don't know if the person who cleaned it removed it or not. I sure works like a dam now.

that guy was trying to sell his part. You can clean your evap core, without taking it out, it just takes a little work. IF yours is REALLY nasty, it may require removing it, but once it's out of the car, its a gravy job to clean it out. If your car has never been converted to the newer r-134a refrigerant, I don't suggest releasing r-12 into the air. You should have a competent A/C shop vacuum down the system to ensure all traces of r-12 and moisture are removed from the system, then buy an R-134a retro fit kit and refill the system your self if you have to take the evap core out to clean it.

He did mention the older refrigerant that would be in the car and that it would have to be recharged if the evap core was removed. Therefore, no he did not remove it to clean it.

I believe (though I'm not positive) that it's underneith the air cleaner box. There should be 2 valves there, might have to check a manual to figure out which is which.

All the help I have received here has been fantastic. Thank-you all so much. This seems to be a pretty popular problem with these vehicles and something totally new to me maybe we have helped someone else along the way as well.