A/C-Heater Blower Motor

[AdrianR]

Folks, I'm thinking this is due for replacement - along with a general service of the blend flaps etc - but how do I access it? From the engine bay or from inside the cab?

[Da67goatman]

Both its 2 halve that bolt to the firewall, the heater core is inside with the flaps and the AC and blower motor are on the under hood part.

This is the under dash part.

[VileZambonie]

There really is no general service to the distribution plenum and actuators. Unless there is an issue they are essentially maint. free. So what is the problem? Low flow?

[AdrianR]

... So what is the problem? Low flow?

There are two issues.
1. There is  low/poor air volume/flow even (with the blower at max). The blower motor isn't making any strange noises to suggest it's dying but the airflow seems like it should be better than it is.
2. The A/C temperature is fine but the airflow from the vents seems to decrease as the truck goes faster. At 60mph and with the blower on max, there's just a faint breath of cold air.

Any suggestions as to where I should start looking? 

[acefoxx]

subbed. I would like  some advice on this also. My blazer seems to have a tired blower also.

[VileZambonie]

Make sure the vacuum reservoir is hooke up and the heater control is tapped into it also.

[AdrianR]

Brief update for info.

Replaced the blower motor ($20 for a reman unit from Pep Boys) and things are better.
The volume of air seems the same (I guess it would be as the blower wheel and motor rpm are the same) but there seems to be more 'oomph' at the dash vents now.

[1979C20]

You could always use a late model blower motor for more air flow.

[Skunksmash]

You could always use a late model blower motor for more air flow.

Do you happen to know which late model, specifically, would push more air? I am having the same problem. Low air volume making it out the vents.

Also my air cuts off completely after its been running on the high fan setting for a few minutes.

[Grim 82]

I use the blower motor from a 94 chev pickup. If you have AC it will be a direct replacement, but I have heard that they will not fit in a non-AC box. It's been my experience that low air flow in the vents is almost always because of a vacuum leak not allowing the blend flaps to work properly.

[Skunksmash]

Hmm... where would you recommend looking for that vacuum leak? Vacuum leaks are probly easy, but I've never been good at them. I have no idea where all they ran vacuum lines on these old trucks.

[Grim 82]

Start at the reserve can on the firewall and trace that hose back to its source and make sure that it's hooked up and fits tight. I have mine hooked directly to the carb.

[cvbear]

I have AC issues as well, I am curious as to why you have the vacuum hooked directly to the carb and not to the canister.

[Grim 82]

I have the canister hooked directly to the carb instead of having a fitting threaded into the intake manifold. The only lines I run are directly from the carb. PCV, brake booster, ported to the vac advance, and manifold to the HVAC reserve can.