Heater not blowing very hard

[robmoore11]

The last owner said the heater in this truck used to blow pretty hard until he went hunting one year and hit a bump pretty hard. He said that was when it crapper out. It still works but it is having problems now. Floor vent doesn't work. It constantly blows out of the vents on front of dash and the fan barely has any pressure. He said he thinks it is the heater unit itself , the dash piece to choose heat etc 'not sure of the actual name' what do you guys think? The dew is starting in the mornings here again and I'd like to get this fixed so I can see out of my windows for more than half of my trip to work in the morning.

 

[Compu Doc]

Check your vacuum supply lines to and from the heater controls and doors. It may have a disconnected hose.

 

[MIDNIGHT RIDER]

If I understand your situation correctly, part of your problem seems to be the vacuum selector switch, which is what all the control-levers are connected to.

It has been my observation that the original equipment vacuum selectors that came in these trucks are not very durable.

Twenty some odd years ago, I replaced mine with an aftermarket unit from the parts-store, ECHLIN maybe, or STANDARD; whatever, it has been problem-free for many years.



As for the blower not being very strong :

First, remove the blower and clean out all the junk that has collected in it's housing that is preventing it from working.

Then, remove the A/C evaporater box and clean it likewise, plus thoroughly cleaning the evaporater of the thick wet mat of dog-hair and

Access the heater-core and clean out it's residence likewise.



Blow out all the ducts as best you can.


Make certain all the little doors in the system are opening and closing when they should.



If after all that you still desire stronger air-speed, RELAY both sides of the blower circuit, right at the blower.

 

[robmoore11]

The company that had owned this truck 6+ years ago removed ac pump and all piping to go with it but left any other components. So is it necessary to remove and clean? And where is the fan located? I am very un-familiar with heating systems.

 

[Compu Doc]

The fan itself is located under the hood in the heater core box. Follow out your heater hoses and you will see the box I am referring to. It is on the passenger side. The part that needs to be cleaned out would be accessed from inside the cab.

 

[OLDBULL8]

Remove the glove box, behind that is an access to the fan.

 

[MIDNIGHT RIDER]

Cannot one pull the blower from under the hood on the 1990 model ??

 

[damac]

On my 85 I had to yank the dash and rework all the blend doors with new foam because the main hinge is thin plastic and broke. And some of the doors work off vacuum. So its best to make sure all the vacuum hoses are good and to work it with the dash out before putting back together.

That will help, but the stock blower still seems to only put out like half the power of a modern truck. Look into modding the blower motor like others have on this forum to get it to spin faster. I am going to try it when I get time.

Also I think its more of a selection thing when it comes to the selector because although it only gets into teens in our winters I swear if the truck is warmed up before takeoff, the heater will put out enough heat that you want to turn the blower speed down and change the vent direction to directly off your body.

 

[Kevin 007]

My 1990 blows quite hard, I have never had an issue with it not beign able to keep up; it is all stock and never been apart.

 

[alienturtle]

also pull the actual ac/heater controlls out of the dash.

1) pop the bozel off that goes around the controls and radio by pulling ******* it

2) use a torex bit and take the 4 screws holding the controls in.

I found my connector and fan speed switch(the one that goes up and down all the way on the left) melted and would only allow me to have low fan speed

just an easy thing to check.

Also If you have a vacuum leak anywhere in the system it defaults to the defrost mode (the top of the dash vents) for safety purposes. The system is designed that way. If you have everything on and look under the glow box under the dash right there you will see a big circle vacuum switch with a plastic arm hooked to it as well as a blue hose. If you push that arm in or closed it should start coming out of the normal vents facing you. If it does you know you have a leak somewhere.

 

[BigRigTech]

My bet is the motor itself - I had the same problem on my 92...It worked on all speeds but it was very weak compared to my 91...I swapped in another used motor from my parts pile and bingo - much stronger....You could see the huge difference between the two when I tested them on the work bench.... I think the bearings were drying out and slowing it down.

 

[Blind Driver2]

Just be see you have vacuum to the AC/heater controls. Mine enters from the passenger side by the battery box then routes to the drivers side. It's just a 1/8" plastic line that breaks easily.

 

[Tarantula]

Clean your connectors

I cleaned all associated connectors, rewired the ground, and my blower perked up quite a bit. I also sealed all of the ducts with weather seal foam and brought my heater system up to a respectable degree of performance. It is worth a try!

The last owner said the heater in this truck used to blow pretty hard until he went hunting one year and hit a bump pretty hard. He said that was when it crapper out. It still works but it is having problems now. Floor vent doesn't work. It constantly blows out of the vents on front of dash and the fan barely has any pressure. He said he thinks it is the heater unit itself , the dash piece to choose heat etc 'not sure of the actual name' what do you guys think? The dew is starting in the mornings here again and I'd like to get this fixed so I can see out of my windows for more than half of my trip to work in the morning.