Troubleshooting AC + Heater
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Troubleshooting AC + Heater
OK, now that I am getting more familiar with my son's truck I think I can tackle a few more complicated problems. Next on deck is the AC/Heater not working.
1989 F350 with 460 + manual
NOTE: This system was previously retro-fitted and converted to R134a.
With the truck running, turning the blower on does nothing whatsoever on any fan setting. It seems to do this regardless of what setting it was on re: AC normal, AC max, Vent, Heater, etc and equally so regardless of temperature selection. The selector bars themselves do NOT appear broken and feel quite solid.
From my time in the engine compartment I know the AC compressor seems to spin freely when the truck is off, so I don't think it's seized which is what the previous owner thought it might be.
This is what I have planned to check, in order:
Thoughts?
1989 F350 with 460 + manual
NOTE: This system was previously retro-fitted and converted to R134a.
With the truck running, turning the blower on does nothing whatsoever on any fan setting. It seems to do this regardless of what setting it was on re: AC normal, AC max, Vent, Heater, etc and equally so regardless of temperature selection. The selector bars themselves do NOT appear broken and feel quite solid.
From my time in the engine compartment I know the AC compressor seems to spin freely when the truck is off, so I don't think it's seized which is what the previous owner thought it might be.
This is what I have planned to check, in order:
- Fuse for heater/AC (30amp)
- Heater blend door actuator (need to figure out where it is)
- Heater motor
- Heater blend door itself (once I find the actuator)
Thoughts?
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Well, the fuse is good. So now I need to check the wires for shorts. I am having to do this for my wife's daily driver too, and I need the practice learning what to do with electrical. I know what I'm doing this weekend.
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OK, I found another few details to share.
First I believe this is the ac/heat blend door actuator
air and heat blend door actuator
It seems to work fine. It moves the cable and the pivot back and forth when moving the selector between Cold and Hot.
Additionally, the selector to what kind of Air or Heat seems to work fine. My original note above was missing the word "not" before broken so I edited that.
In the engine compartment, above the heater blower motor is a little unit that I believe is a vacuum switch of some sort?
what is this part called
The switch seems to move back and forth freely, but it makes a wheezing sound when I pivot the joint back and forth by hand. It doesn't seem to be affected by the blend door actuator so I am guessing it's separate from that. But very quickly looking at the white tube that runs from there over to (somewhere else) is it clear that line is gonzos.
I think this line is toast
So, what do I do with that white tubing line? That seems to be the culprit.
First I believe this is the ac/heat blend door actuator
air and heat blend door actuator
It seems to work fine. It moves the cable and the pivot back and forth when moving the selector between Cold and Hot.
Additionally, the selector to what kind of Air or Heat seems to work fine. My original note above was missing the word "not" before broken so I edited that.
In the engine compartment, above the heater blower motor is a little unit that I believe is a vacuum switch of some sort?
what is this part called
The switch seems to move back and forth freely, but it makes a wheezing sound when I pivot the joint back and forth by hand. It doesn't seem to be affected by the blend door actuator so I am guessing it's separate from that. But very quickly looking at the white tube that runs from there over to (somewhere else) is it clear that line is gonzos.
I think this line is toast
So, what do I do with that white tubing line? That seems to be the culprit.
Fleet Mechanic
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That is the vacuum motor that works the Recirculate/Fresh Air door just above the passengers foot area. The decay of that white vacuum hard line is very common. Cut it back to good solid plastic, and use a tight-fitting length of rubber hose to connect it back up. You may have to unwrap some of the harness tape, my Bronco's white line was crumbly for a few inches inside the tape, then it was good.
If your heater blower is not running at all, that is a separate problem.
If your heater blower is not running at all, that is a separate problem.
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@Torky2
Thanks for the advice. Would a local auto parts store have the rubber hose? What size would that be?
With that line decayed, the recirc/fresh air door would function again? I'm not getting anything though on the system - no fan, nothing. So I'm guessing I've got something else that's a problem too. Would the vacuum motor lack of vacuum prevent the whole thing from working?
Thanks for the advice. Would a local auto parts store have the rubber hose? What size would that be?
With that line decayed, the recirc/fresh air door would function again? I'm not getting anything though on the system - no fan, nothing. So I'm guessing I've got something else that's a problem too. Would the vacuum motor lack of vacuum prevent the whole thing from working?
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Fleet Mechanic
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I watched the video... he's clueless on what that vac motor does! And don't "put some silicone on it before you slide it together". There is no need for silicone anything.
Snip of a 1" length or so of good white hardline, and bring it with you to the parts store. That way can test-fit for a tight fit. Use regular emissions/vacuum hose. IIRC, the OD of the hardline is at/around 1/8", so you're looking for a hose with ID around/ a bit smaller than that.
Snip of a 1" length or so of good white hardline, and bring it with you to the parts store. That way can test-fit for a tight fit. Use regular emissions/vacuum hose. IIRC, the OD of the hardline is at/around 1/8", so you're looking for a hose with ID around/ a bit smaller than that.
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From: Easton,Ks
If the blower does not turn on at any speed then you have a bad fuse #9 (30 amp) or a bad selector switch in the dash or and open wire.
First check for power at each end of fuse #9 with a loading (not LED) test light with the key in the run position.
The back of the fuel panel being bad has also caused this problem.
/
First check for power at each end of fuse #9 with a loading (not LED) test light with the key in the run position.
The back of the fuel panel being bad has also caused this problem.
/
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OK, I have the vacuum hose from the vacuum motor exposed now. Lots of 20+ year old tape later I can see what I'm working with. The bad news is most of that hose line is crap - decayed into dust pretty much right up to the point where it was protected by the wire loom + tape.
I also picked up the wrong size hose. I got the 1/8" OD one that would replace the existing one, not one that would fit over it. I'll grab that tomorrow and put it on both ends. Now that I can see the rubber sleeve that it mounts to the motor with I can pick something to connect the two tubes with at each end if necesary.
Fuse #9 is what I visually inspected previously. It seems to be good. EDIT: I tested with what I think is a good ground, and I got no light on the tester for that fuse. I'll swap it and see what happens.
EDIT#2 - I realized in my fuse packet for my RV I also had a fuse tester device. I used that on the existing & newly installed 30A fuse, and it lit up on both. I think they were OK and I just wasn't getting a decent ground on the prior tester.
I also picked up the wrong size hose. I got the 1/8" OD one that would replace the existing one, not one that would fit over it. I'll grab that tomorrow and put it on both ends. Now that I can see the rubber sleeve that it mounts to the motor with I can pick something to connect the two tubes with at each end if necesary.
Fuse #9 is what I visually inspected previously. It seems to be good. EDIT: I tested with what I think is a good ground, and I got no light on the tester for that fuse. I'll swap it and see what happens.
EDIT#2 - I realized in my fuse packet for my RV I also had a fuse tester device. I used that on the existing & newly installed 30A fuse, and it lit up on both. I think they were OK and I just wasn't getting a decent ground on the prior tester.
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Got the vacuum line put on before it got dark tonight.
vacuum line
There's a similar fix on the other end of the black tubing. I used 5/32" OD over the 1/8" OD original line directly inserting the old tube into the new one. Compressing the lever doesn't seem to leak out either fix.
As for the power - is the connector on the left the proper one for the heater blower or is it the one tucked under the right reflected below?
which power is it
The bottom photo has cables that are fixed to the shell which I believe is a ground for some of the A/C apparatus, whereas the one in the top photo seems to go to the motor itself. I'm thinking the top photo one is right?
vacuum line
There's a similar fix on the other end of the black tubing. I used 5/32" OD over the 1/8" OD original line directly inserting the old tube into the new one. Compressing the lever doesn't seem to leak out either fix.
As for the power - is the connector on the left the proper one for the heater blower or is it the one tucked under the right reflected below?
which power is it
The bottom photo has cables that are fixed to the shell which I believe is a ground for some of the A/C apparatus, whereas the one in the top photo seems to go to the motor itself. I'm thinking the top photo one is right?
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Ah, found another thread that has part numbers I may need. Adding https://www.ford-trucks.com/forums/1...ne-150-v6.html here to make sure I can find it again. 