88 burb blower motor keeps blowing fuse and poor air flow.

[Stopman33]

Hello y'all. Having a bit of trouble with my 88' burb. Since I have owned it the HVAC has never worked right. The truck has always had terrible air flow since I have owned it, I have had zero defrost and air seems to come out of the dash and feet vents but it's pretty weak. I Also have noticed that I have poor heat, I was told the heater core was replaced and both heater hoses are warm to the touch.

Just recently I lost all fan speeds but high, I replaced the blower motor resistor and it worked for a few hours and then it blew the 25amp blower motor fuse. I replaced the fuse and it has blown again after I turned the HVAC on.

What could be causing these issues? I am suspect of a little plastic clip as far as the no defrost issue but I do not know where it is located. Would that also fix the poor heat? and now this blowing fuse? I have been super confused.

 

[PrairieDrifter]

A/c or non a/c?

I would pull the blower motor itself and make sure it spins freely. Could need replaced, pulling too many amps. I would also clean the ground connections to the blower motor and see if that helps.

The poor heat could indeed be the clip, which is in the inside hvac box, have to pull to fix. Check to make sure blend door cable is attached and adjusted first. On top behind glovebox.

I'm not positive on 88. The zone control should be controlled by vacuum, there's a vacuum canister on the drivers side firewall. Runs from engine to canister to passenger firewall inside to the controls. Make sure that's all good, especially the hose. The zone switch is a vacuum switch, which could also be bad.

 

[gmbellew]

The air flow is vacuum controlled flaps. There is a vertical duct piece under the dash that you can take off and see the operation. Sometimes a clip gets broken. The blower power issue could be the resistor or relay being bad. Both are under the hood, or at least they are in my 90 with air conditioning.

 

[squaredeal91]

Check the above for flow and fan issues. The reason it only runs on high is because the blower motor resistor has failed. Its located near the fan on blower housing.

 

[Stopman33]

A/c or non a/c?

I would pull the blower motor itself and make sure it spins freely. Could need replaced, pulling too many amps. I would also clean the ground connections to the blower motor and see if that helps.

The poor heat could indeed be the clip, which is in the inside hvac box, have to pull to fix. Check to make sure blend door cable is attached and adjusted first. On top behind glovebox.

I'm not positive on 88. The zone control should be controlled by vacuum, there's a vacuum canister on the drivers side firewall. Runs from engine to canister to passenger firewall inside to the controls. Make sure that's all good, especially the hose. The zone switch is a vacuum switch, which could also be bad.

Yes A/C. I will start with removing the motor to check that.

 

[Stopman33]

Well I dug into the blower motor first. Removed it and it spun freely without issue. I went and cleaned the ground and positive connections and it seems to be working well now.

I removed my glove box to gain access to that plastic clip, sure enough it’s broken. I’m assuming this is my air flow issue. I need to also clean the mouse nest out of the box because of course they got in.

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[Stopman33]

Seem to be having trouble removing the clip. I wanted to see if I could temporarily “fix it” since I can’t make it any worse. I can’t remove the little metal pin.

 

[Stopman33]

Arghh… finally got it out after too long of trying lol. I will need to order a new one. So far after cleaning the vents out my air flow situation and the temperature of the heat is substantially better! I’ll order up that new clip and it should get my defrost working again. After that’s fixed I can dig into the air conditioning!

 

[gmbellew]

Seem to be having trouble removing the clip. I wanted to see if I could temporarily “fix it” since I can’t make it any worse. I can’t remove the little metal pin.

It is just a friction fit. Use a pliers to push it up from the pointy end. That should help get it started and then you can remove it

 

[Jgonick]

I had to fix mine several years ago- I believe LMC has it for roughly $6 and on amazon there are aluminum ones. AMAZON LINK

 

[Stopman33]

I had to fix mine several years ago- I believe LMC has it for roughly $6 and on amazon there are aluminum ones. AMAZON LINK

Right on! I ordered that Amazon clip. When I manually held the door closed I was getting air out of the defrost. I could not for the life of me find a video or pictures of removing the ducting behind the dash to get to the clip.

 

[Stopman33]

Well the fuse blew again… maybe there’s an issue with the new blower resistor?

 

[Ricko1966]

Well the fuse blew again… maybe there’s an issue with the new blower resistor?

More likely the blower motor itself,drawing too many amps.

 

[Stopman33]

More likely the blower motor itself,drawing too many amps.

I’ll try running the motor by itself with a separate fused circuit to see if it blows that fuse. From what I’ve heard you can run a gmt400 blower motor in a square body if you swap the fan? Probably would end up doing that, I think I’ve got a spare motor around somewhere…

 

[Ricko1966]

I’ll try running the motor by itself with a separate fused circuit to see if it blows that fuse. From what I’ve heard you can run a gmt400 blower motor in a square body if you swap the fan? Probably would end up doing that, I think I’ve got a spare motor around somewhere…

It's not a different motor on the later squares,squares got the motor before the GMT 400. So the difference is early and late squares. Also as you decrease voltage the amperage draw increases,so running a straight 12v to the motor won't be an indicator as to what amperage the motor draws after the resistor drops the voltage.You could check with a clamp on ammeter.