Hey gang,I got a non-Camaro Chevy question and this place has some of the most knowledgeable folks of anywhere I know.
I recently bought a '99 Silverado 1500 4X4 with the 5.3 engine,needs a few things but overall a nice truck given over 200K miles on the clock.
My problem is with the heater,it's just not moving much air from the various ports,before I tore into it the windows wouldn't defog at all.
What I've done so far is pulled the cover and removed the blend door actuator thinking it may be the culprit,I had a plastic gear inside the actuator break on my old S10 and a replacement was the fix so I hoped it would be on this truck as well.
I've also replaced the cabin air filters which were filthy,after that and moving the blend door by hand I now have better heat and some defroster air but still not what I would consider normal.
There is good heat heat so the heater core is fine,the fan seems to be kicking it in all settings and makes plenty of noise like its working but still not moving as much air as I would expect. Maybe because the bottom cover is still off?
Getting back to the blend door actuator,I took the cover off it only to find nothing broken,the gears turn freely and the motor spins free,I hooked it up with the cover off and with the gears out, the motor started spinning as soon as I turned the heater to the on position. I put the gears back in and it spun the gears as far as it could go and stopped.I tried switching the selector **** to a different setting to see if it would reverse and nothing,it only spins one direction until it goes as far as it can then stops. So now I'm not sure if the switch is bad or if its something electrical with the blend door actuator itself,I hate to start throwing parts at it hoping for a fix.
The blend door actuator isn't very expensive so I might buy one but the heater controls are a little pricey,I could buy both but not sure even that will be a fix.
Hate to replace parts that aren't bad especially if they don't fix the problem.
Any insight here would be much appreciated,if the dash has to come out I'll probably have to put it in the shop as I just don't have enough free time to go in that deep.
Thanks in advance for any thoughts.

 

I would start with replacing the actuator. It's not uncommon for them to fail, and they're the most likely culprit for the issue you're having.

 

Did you read the whole post? I figure I'll get one since I have it apart and they aren't real expensive but it doesn't answer my question completely.

 

I did, and ok, you only had one question: "the fan seems to be kicking it in all settings and makes plenty of noise like its working but still not moving as much air as I would expect. Maybe because the bottom cover is still off?"
If you're referring to the interior trim cover, then no, that wouldn't affect air output.
And, your truck has 2 blend doors/actuators, one on the drivers side, one on passenger side. If those aren't working, or not working in sync, you'll have output issues.

 

Yes just the cover over the heater under the glove box. 2 actuators? I only found one kind of in the middle pass side of trans hump,will have to look for another on driver's side I guess.

 

Get a haynes manual for the truck and read up. Inexpensive and valuable info.

 

Well maybe I should but I bought this truck as a stopgap until I can get something newer hopefully later this year.
My daily driver '99 Dodge Dakota I had hoped would make it a few more months but the tranny failed so I bought this truck to get me by for a while.
I inherited a half interest in a home and a little money,my sister and I will be doing a bit of remodel work on the house and then selling it.
It's a nice little ranch house in Central Oregon on 5 acres owned free and clear and it's a hot market so we hope to do pretty well on it.
With a little luck I'll be able to nearly pay off my mortgage and that will allow me to buy a newer truck,meanwhile I could use a working heater in the beater. lol

 

Well I made progress this weekend after some more online research,turns out this truck actually has 3 different actuators.
The one I pulled (Blend door) had nothing wrong with it,it's the hot to cold actuator. Once I turned the right **** it went both ways doah!
So the mode actuator is on the other (driver's side),it controls where the air comes out ,defrost to floor and in between.
Not fun to get to but after pulling some duct work I could see it well enough to see if was moving when I turned the **** and it did nothing so hopefully it's the problem.
I bought Dorman replacement for $50 after quite a battle to get the old one out. I Sure hope it's not the switch lol.
The 3rd actuator is the fresh air or recirculation air door and it's way up in the dash,hopefully it's okay because it's a nightmare to get at.

 

Good deal.

 

I hope so ha ha,probably going to be harder getting it back in and timed right than taking it out,just crossing my fingers and toes that it fixes the problem.