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The other day the climate controls stopped work in my truck, I have the digital display and button controls. The heater is working fine but it is stuck in defrost, when I try to change the output to the face vents or feet the display clicks and shows that is changes but no change happens, it stays locked in full defrost only. Sounds like its a vacuum issue that I will have to chase, my question is is this typically a bad vacuum pump or could it be the heater control valve that is right next to the pump? I checked and the hub connections looked good and intact, I will double check after work today. Anyone else experience this? Or have any advice on where to start looking?
When you first turn your key to the ON position after the truck has been sitting a bit, like overnight, do you hear the vacuum pump come on? Or if you leave the key in ON position and unplug hose from the pump to reservoir does it kick on?
When you first turn your key to the ON position after the truck has been sitting a bit, like overnight, do you hear the vacuum pump come on? Or if you leave the key in ON position and unplug hose from the pump to reservoir does it kick on?
When I put the key in ON the pump comes on and keeps running, I did a quick visual inspection and the hub hoses are tight but it could be leaking anywhere in the hubs. My question is, would a failing vacuum pump cause this? or is this 9 times out of 10 a leak somewhere in the system?
Is there a way to disconnect hubs at the pump? Assuming the leak is in one of the hubs somewhere and not the pneumatic that run behind the dash, could I disconnect the hub vac lines and plug those on the vacuum? If the leak is in the hub this would allow the system to pull and vacuum, get my climate controls back to normal and also confirm there is a leak down stream at the hub somewhere?
When I put the key in ON the pump comes on and keeps running, I did a quick visual inspection and the hub hoses are tight but it could be leaking anywhere in the hubs. My question is, would a failing vacuum pump cause this? or is this 9 times out of 10 a leak somewhere in the system?
Follow the line coming from the pump to the reservoir. Unplug it and put your finger over the nipple on the pump. Does the pump shut off after it sucks tight to your finger? If so the pumps fine. Check other lines and the 4wd pulse solenoid by isolating it from the system.
Follow the line coming from the pump to the reservoir. Unplug it and put your finger over the nipple on the pump. Does the pump shut off after it sucks tight to your finger? If so the pumps fine. Check other lines and the 4wd pulse solenoid by isolating it from the system.
Thanks, I'll plan on doing this one of the warmer days this week. If I do find it is somewhere in the 4wd system, can the line that goes to the reservoir or the pulse solenoid be disconnected and capped at the vacuum pump? I would lose esof but it would tell me the issue is in the 4wd assemblies (hub, hoses, pulse solenoid) and not in the dash pneumatic lines.
Thanks, I'll plan on doing this one of the warmer days this week. If I do find it is somewhere in the 4wd system, can the line that goes to the reservoir or the pulse solenoid be disconnected and capped at the vacuum pump? I would lose esof but it would tell me the issue is in the 4wd assemblies (hub, hoses, pulse solenoid) and not in the dash pneumatic lines.
Thanks again
Yep, I’ll try to post a pic later of the line to cap off.
Even if your lines at the hub are tight they may have a crack in them somewhere. My leak was the plastic nipple that the rubber hose from the hub connects to at the frame rail. It had a crack in it.
Yep, I’ll try to post a pic later of the line to cap off.
Even if your lines at Ed at the hub are tight they may have a crack in them somewhere. My leak was the plastic nipple that the rubber hose from the hub connects to at the frame rail. It had a crack in it.
That's what I am afraid mine may be, it started cooling down (10F) here in MN when this started and I'm thinking something got brittle and cracked somewhere, I want to try and isolate/locate the leak and then chase that when its a little warmer, it would be nice to have some control over my heat again.
Theres only 2 vacuum lines on the pulse solenoid. One goes to the hubs and one is the vacuum source. Plug the line coming from the vacuum source. The pulse solenoids do go bad and will vent your vacuum source to the atmosphere so your pump will never shut off. I just had a bad one last month on a gasser F250, which doesn't mean it's your problem too but a good place to start.
Theres only 2 vacuum lines on the pulse solenoid. One goes to the hubs and one is the vacuum source. Plug the line coming from the vacuum source. The pulse solenoids do go bad and will vent your vacuum source to the atmosphere so your pump will never shut off. I just had a bad one last month on a gasser F250, which doesn't mean it's your problem too but a good place to start.
I actually have one of these on order, should show up in a couple days, I read a thread from another site that pointed this out as the issue for a guy that had similar issues. I was going to try and isolate the leak and if that didn't work I was going to replace the solenoid and the vacuum pump.
Today on the way home from work the controls began responding to the buttons, it worked for about 5 minutes then went back to full defrost. They worked fine completely out of the blue, then went right back to doing what is has the last week. When I got home I pulled off the line that goes to the vacuum reservoir and plugged it, the vacuum pump shut off almost immediately, but I still didn't gain control of the climate control direction selections.
Today on the way home from work the controls began responding to the buttons, it worked for about 5 minutes then went back to full defrost. They worked fine completely out of the blue, then went right back to doing what is has the last week. When I got home I pulled off the line that goes to the vacuum reservoir and plugged it, the vacuum pump shut off almost immediately, but I still didn't gain control of the climate control direction selections.
You won’t get control of climate control until you get rid of the leak, either by fixing it or at least blocking off that area. Right next to the hose from the vacuum pump to the reservoir there should be a T that comes out of the reservoir. This T feeds the line that goes to your HVAC line and also to the pulse solenoid. I’m betting if you block off the part of the T that goes to the pulse solenoid you’ll regain control of your HVAC vent choice.
Unplug the plug with 2 lines on the pulse solenoid. Plug the red supply line. The vacuum pump should stop running in less than a minute or so. Then your heat controls should work fine.
Unplug the plug with 2 lines on the pulse solenoid. Plug the red supply line. The vacuum pump should stop running in less than a minute or so. Then your heat controls should work fine.
Tried this this afternoon, the vacuum pump shut off after about a minute like you said and the heat controls worked fine. Bad 4wd pulse solenoid?
