85 W150 intermittent heater issue

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Brucecmc

Senior Member
Joined
Nov 21, 2016
Posts
123
Reaction score
1
Location
At the parts store
Ram Year
1985 Power Ram W-150
Engine
318 V8 5.2L
85 W150 intermittent heater issue - RESOLVED!

Alright you smart mopar fanatics. Next project in my never ending fixes to my 85 W150 4x4.

So, I flipped on my defroster the other day, and she started blowing. I came out to check on defrost and discovered it had stopped blowing. So turned it off, flipped back on - nada. Proceeded to destination (having left defrost on) and about half way there, it came on. Ran for a bit, then shut off.

That has been the symptoms since. Defrost or heater. I noted ithat as I shift from heater to defrost that there is a brief clicking sound that Eminates from the control panel. Some times it works, most times it does not.

I haven't dug into the issues with the blower stuff behind the glove box and all that. Just wanted to get a feel if anybody else has ran into this type issue.

Bruce
 
Last edited:
OP
OP
Brucecmc

Brucecmc

Senior Member
Joined
Nov 21, 2016
Posts
123
Reaction score
1
Location
At the parts store
Ram Year
1985 Power Ram W-150
Engine
318 V8 5.2L
Alright you smart mopar fanatics. Next project in my never ending fixes to my 85 W150 4x4.

So, I flipped on my defroster the other day, and she started blowing. I came out to check on defrost and discovered it had stopped blowing. So turned it off, flipped back on - nada. Proceeded to destination (having left defrost on) and about half way there, it came on. Ran for a bit, then shut off.

That has been the symptoms since. Defrost or heater. I noted ithat as I shift from heater to defrost that there is a brief clicking sound that Eminates from the control panel. Some times it works, most times it does not.

I haven't dug into the issues with the blower stuff behind the glove box and all that. Just wanted to get a feel if anybody else has ran into this type issue.

Bruce
 

crazzywolfie

Senior Member
Joined
Apr 6, 2013
Posts
16,422
Reaction score
3,183
Location
under the truck
Ram Year
81 93
Engine
5.2
well you are best to start by just hot wiring the motor to see if it is working properly. does it blow heat out the vents in the vent or either of the a/c positions? there is 2 fan control settings. i know it is pretty common to have the heater control switch to crap out after a while. i have mine bypassed so the fan is always on but it is better than none.
6937Uu2jfkxe85t14EUCA8RzkLEq2QiNsxwSg=w657-h369-no.jpg
 

dsexpress

Member
Joined
Mar 6, 2012
Posts
62
Reaction score
4
Ram Year
2012 RC Express (sold) 2017 Ram RC Express
Engine
hemi 5.7
Sounds like a bad blower motor resistor to me. Just my 2 cents
 
OP
OP
Brucecmc

Brucecmc

Senior Member
Joined
Nov 21, 2016
Posts
123
Reaction score
1
Location
At the parts store
Ram Year
1985 Power Ram W-150
Engine
318 V8 5.2L
No WOLFIE, when it's not working, no switch position (a/c, heat, def,etc) function. Don't know how to hot wire the blower motor but will ask mr Google / Mrs. YouTube
 

crazzywolfie

Senior Member
Joined
Apr 6, 2013
Posts
16,422
Reaction score
3,183
Location
under the truck
Ram Year
81 93
Engine
5.2
ok. the only reason i ask is there is 2 heater circuits so if 1 is not working the other sometime is. still could be a bad switch like i posted a picture of. not unheard of. have you checked to see if it is a fuse or if there is power at the fuse with the key on? could be a bad fusible link.

hotwiring the blower motor is as easy as unplugging it and running a positive and ground wire to it under the hood but i would probably start by testing at the fuse panel. a fusible link is way easier to fix than anything else that could be wrong with it.
 
OP
OP
Brucecmc

Brucecmc

Senior Member
Joined
Nov 21, 2016
Posts
123
Reaction score
1
Location
At the parts store
Ram Year
1985 Power Ram W-150
Engine
318 V8 5.2L
Roger. But I wud think if it were a fuse, it wouldn't ever work, no? Those dang fusible links are always in question aren't they. Roger on the "hot wiring" I just read that in the Haynes manual (it actually had something useful). So, I'll yank the blower motor, hot wire, make sure it runs continuously and if so, look at other options. There's a little troubleshooting process in that Haynes manual I'm gonna attempt (part of which is ur suggestion of hot wiring)
 

crazzywolfie

Senior Member
Joined
Apr 6, 2013
Posts
16,422
Reaction score
3,183
Location
under the truck
Ram Year
81 93
Engine
5.2
ya a fusible link can cause issue. the fuse panel is still the best place to test the fusible link tho. if you have no power at the heater fuse with the key in the run position then it is possible that the fusible link is bad. if there is power at the fuse then the issue is likely somewhere else in the wiring.

you should be able to leave the blower motor in the heaterbox and hotwire it. you can hear the motor turn on
 
OP
OP
Brucecmc

Brucecmc

Senior Member
Joined
Nov 21, 2016
Posts
123
Reaction score
1
Location
At the parts store
Ram Year
1985 Power Ram W-150
Engine
318 V8 5.2L
So yea, it seems the blower is working fine. Hot wired and she runs nice and smooth.
 
OP
OP
Brucecmc

Brucecmc

Senior Member
Joined
Nov 21, 2016
Posts
123
Reaction score
1
Location
At the parts store
Ram Year
1985 Power Ram W-150
Engine
318 V8 5.2L
Assuming my "back probe" connections were good, there was NO voltage at the terminal so next hop looks like that resistor dsexpress referred to. But it's getting dark, my light is friggin burned out (so I find now) and I can't see jack. Will pick up tomorrow. Getting this t/s tip from the hayn s manual chapter 3 (3-6). Will post results of that test. Getting closer to that heater control circuit WOLFIE. Does that circuit work with both the AC and heater controller ?
 

crazzywolfie

Senior Member
Joined
Apr 6, 2013
Posts
16,422
Reaction score
3,183
Location
under the truck
Ram Year
81 93
Engine
5.2
best spot to check is the fuse panel with the key in the run position to see if the heater circuit is getting any power. and go from there.

there is 2 difference resister circuits. 1 of them allows the fans to spin faster on high than the other circuit. the input on my 93's switch failed so i had to bypass it. i got my remote start hooked up to the slower spinning circuit and hot wired the faster spinning circuit so the motor is always spinning but it is better than no heat. i usually unplug the blower motor in the summer.
 
OP
OP
Brucecmc

Brucecmc

Senior Member
Joined
Nov 21, 2016
Posts
123
Reaction score
1
Location
At the parts store
Ram Year
1985 Power Ram W-150
Engine
318 V8 5.2L
Hmmm. Are the 2 different resisters for the fan in that one control circuit that you sent the pic of ? I don't wanna by-pass. Really wanna try and fix this bugger if possible. Every time you respond I get something new to look up. Lol. "Remote start"
 

crazzywolfie

Senior Member
Joined
Apr 6, 2013
Posts
16,422
Reaction score
3,183
Location
under the truck
Ram Year
81 93
Engine
5.2
the picture i posted before is the switch. depending which setting you have the heat on effects how high of a high speed the blower motor blower motor has. the blower motor resister is behind the glove box but above the heater box but i would still check for power at the fuse first. checking for power at the fuse will help you get a better idea where your issue may be.

lol. ya a remote start is nice especially if you live somewhere cold but you almost need a fuel injected vehicle to have one. for me it was the best $20 i have spent on this thing.
 
OP
OP
Brucecmc

Brucecmc

Senior Member
Joined
Nov 21, 2016
Posts
123
Reaction score
1
Location
At the parts store
Ram Year
1985 Power Ram W-150
Engine
318 V8 5.2L
Oh. You mean a literal "remote start" like newer vehicles have. Roger on the fuse box. I'll check that first thing tomorrow.
 

crazzywolfie

Senior Member
Joined
Apr 6, 2013
Posts
16,422
Reaction score
3,183
Location
under the truck
Ram Year
81 93
Engine
5.2
haha ya remote start just like newer vehicle. it may cause you to use more fuel in the winter time but is so worth it.

ya you should see 12v at it with the key in the run position if everything is working properly.
 
OP
OP
Brucecmc

Brucecmc

Senior Member
Joined
Nov 21, 2016
Posts
123
Reaction score
1
Location
At the parts store
Ram Year
1985 Power Ram W-150
Engine
318 V8 5.2L
Cool. So, when I bought the truck, the fella told me the AC wasn't working. Could correcting this issue with the heater have ANY bearing on the non functioning AC? Granted the AC problem cud be absolutely anything. I'm just wondering if the power and controls for the heater would affect the AC since it's the same control unit.
 

crazzywolfie

Senior Member
Joined
Apr 6, 2013
Posts
16,422
Reaction score
3,183
Location
under the truck
Ram Year
81 93
Engine
5.2
it is possible but not likely. the reason you don't have a/c is likely caused by a leaking seal somewhere that let all the refrigerant out. i know i am in the same boat with my 93. it had a/c when i got it but it no longer has anything in the system. i have considered fixing and recharging it but it really don't get hot enough in the summer for me to justify it.
 
OP
OP
Brucecmc

Brucecmc

Senior Member
Joined
Nov 21, 2016
Posts
123
Reaction score
1
Location
At the parts store
Ram Year
1985 Power Ram W-150
Engine
318 V8 5.2L
I'll have a stroke if I don't get it fixed by summer. 100 degrees and 1000% humidity. Critical piece of equipment.
 
Top