Is there a cabin filter on a 77 Silverado?

[slam59]

My wifes 77 Silverado with a 454 has low air flow coming from the a/c/. It sounds like its blowing hard but it really does not blow out hard like most do. I read awhile back about people cleaning theor evaporator core and putting new filters on the cabin filter. Did the 1977 years of Silverados have a cabin filter? Anyone have pics of theirs torn apart showing the mess that accumalates in there restricting air flow? I remember one site had pics of different peoples torn apart and it was unreal what stuff was in there. They said after cleaning it all out it was night and day difference how much more air flow came out when the a/c was on.

[cory d]

i dont know if it as a filter but i took my blower put of my 80 and cleaned out a ton of dirt and i dont even live in a dusty are

[andrewmp6]

First gm truck i seen with a cabin filter was a 1999.

['79squared]

I was thinking it sounded more like a muffler bearing lol

[donut]

No cabin filters on the older ones.
Cleaning can make a night and day difference, considering it hasn't been done in 35 years.
While your at it, check the seals where the duct goes into the dash ports. They're probably shot (just a foam seal).
Check the squirrel cage (fan) on the blower motor, it can be broke or spinning on the shaft.
Do all the HVAC functions work? May be a good time to check all of them out.

I've done mostly heat only trucks, all of them were 20 years past due for a cleaning.

[slam59]

Yeah donut, all the funcions work, just does not blow real hard, even when it is set on the highest setting. So what parts exactly do I clean out and where are they located?

[donut]

Personally I'd start with pulling the blower motor and checking that. Does the fan speed change with switch position? (I had an electric cooling fan in front of my radiator that fooled me into thinking my blower motor was fine.)

Check the "squirrel cage" and make sure its intact. Pulling the blower motor should (iirc) give you some access to the plenum and a place to do a quick visual and cleaning, go from there.

I don't have much experience with the AC systems and how they're set up, just started digging into mine a couple months ago, that job got put on hold when my transmission let go. (I don't even know if my AC works, but I'd like to find out before summer.)

[Wrecked1982]

in 77 cabin filter were like pollution , i didnt exist

[esbstuff]

When you have the a/c selected, do you have air flow to the heater vent on the floor? If you do, MOST of the time, this part (see pic) is broken. This is the for the 'blend' door' control. The part number is 3018715 and is $2.39 at the local GM dealer (yes they are still available 35 instock in Chicago 4/25/12). This part can be changed in 10 minutes by removing the glovebox door and removing 4 bolts, 2 9/32 (one on the inside, one on the outside) and 2 10 mm or 2 3/8 (both on the outside) depending on year of your ride and a good pair of plyers to remove/reinstall the small pin. BTW clean out and debris you can find while you have the cover off.

If you don't, then one of the internal doors are block with debris and you will have to dismantle the HVAC box to clean it. The most comomn debris is pens/pencils in that found their way down from the defroster vents...

And on the super rare chance the problem is still no solved, then one of the internal doors has broken, but you should see that when you have the inside box removed...

Originally Posted by slam59

My wifes 77 Silverado with a 454 has low air flow coming from the a/c/. It sounds like its blowing hard but it really does not blow out hard like most do. I read awhile back about people cleaning theor evaporator core and putting new filters on the cabin filter. Did the 1977 years of Silverados have a cabin filter? Anyone have pics of theirs torn apart showing the mess that accumalates in there restricting air flow? I remember one site had pics of different peoples torn apart and it was unreal what stuff was in there. They said after cleaning it all out it was night and day difference how much more air flow came out when the a/c was on.

[ymerej71]

Originally Posted by slam59

My wifes 77 Silverado with a 454 has low air flow coming from the a/c/. It sounds like its blowing hard but it really does not blow out hard like most do. I read awhile back about people cleaning theor evaporator core and putting new filters on the cabin filter. Did the 1977 years of Silverados have a cabin filter? Anyone have pics of theirs torn apart showing the mess that accumalates in there restricting air flow? I remember one site had pics of different peoples torn apart and it was unreal what stuff was in there. They said after cleaning it all out it was night and day difference how much more air flow came out when the a/c was on.

My 79 w/454 has the exact same issue... I hear the air blowing but the output through the vents is just barely there... I'm gonna have to try an tear mine apart and see whats up?!? Hopefully I can figure it out soon.. I'm in Texas and the heat is just around the corner! Please post any updates you have and I'll try and do the same.

[ymerej71]

Originally Posted by '79squared

I was thinking it sounded more like a muffler bearing lol

I've already ruled out the muffler bearing... I greased them just in case! LOL!

[kelsfine69]

I just replaced that little plastic piece again. I'm sure that is the 4th one in 2 years. I went to the wreckers and found a bunch that were still good. now i went to GM and bought a bag of 5 so now hopefully it will last a lot longer not being used and brittle..

[Zebb]

It could be that the blower motor is getting tired too if it has had to work hard for a while.

[motornut]

goes here