2001 F 53 heat & A/C cuts out?

Replacing all of the vacuum hoses would probably cost less than $20 and you can buy as many feet of hose as you need at most auto parts stores.

Hikerdogs.......I think I found at least one place that is bad.
On the vacuum canister under the right head light, there is a short piece of hose that is soft & in bad shape.
Gonna replace that........bet it helps.......a lot!!!!!
Thanks

bsinmich........low side pressure was around 20 psi.
I'd like to check out your GMC some time.

cdl2 wrote:
I don't think I have a vacuum motor, like on the Safari.
Yes....dash heat & A/C.
On the way to the camp ground it worked fine, but on the way home it got really bad!!!!
I've been working on the A/C, adding Freon.

Adding Freon to a system that doesn't need it can cost you a compressor. That is one of the problem with Wal-Mart and everybody else selling the cans but they do help to keep the real AC service men I business.

I'm not sure the AC compressor is shut off----------------the cold air just comes up the defroster vents. With the vents, there is no brain. It is just a valve that controls where the vacuum goes. If no vacuum, a spring moves all the air to the defroster vents, which is the fail safe position (don't want to lose the defroster vents if you need them and lose vacuum.

Yes...a "common" problem for the F-53s. My 2001. Pulling a grade with effort, the computer "brain" sends a message "put all power to the motor" and that cuts out the a/c for the duration of the hill. Once you crest the hill and the effort is less (back into 3rd and then to OD) the a/c comes back on.
A small vacuum tank...maybe. I've put up with this since 2001, always thinking that I've gotta fix this next trip...but it never happened. An annoyance, yes.

That's with the a/c. Never noticed the heater acting the same way.......

Hikerdogs.......I didn't know about the reservoir under the right head light, I'll look for that.
Hope I can get the engine cover off tomorrow & replace all the vacuum lines.
Don't think I saw a check valve( one way valve), I'll look harder for that too.
Thanks.

The vacuum reservoir for the dash Ac is a round ball in the center of the engine compartment (left to right) mounted high in front of the radiator. You may need to stick your head inside and under the hood to see it. There should be a small black and a small blue plastic line going to it. The reservoir should have a 1 way valve on the inlet side to prevent vacuum from bleeding off.

There's also the main vacuum reservoir attached to the frame just below the right headlight. Check the connectors on both reservoirs. They may feel tight but still leak enough to loose vacuum.

We had the same problem on our 2001 F53 chassis. I was able to cure it by putting a film of high vacuum grease on the nipples sticking out of the reservoirs, then reattaching the hoses. If you do this make sure you don't get any grease over the open ports. As the name implies it's meant to withstand high vacuum. You'll have a hard time getting it out of the lines or reservoir if you make a mistake.

Also if your motorhome is stored where any critters can get to it take off the engine cover and check all the lines going to the engine. They like to get in the area and love the salt that gets on the wires and hoses.

Same thing with our 2000 coach on the f53 chassis, it's a vacuum thing. With ours it usually occurs while climbing grades.

Installation of an in-line electric vacuum pump would probably eliminate the problem, but for the short duration of time it happens on our coach, I don't consider it worth the cost & effort.

Without vacuum, the default venting is to the windshield defroster outlets. I added a 2nd vacuum can to mine, but that just delays the inevitable if you're climbing a long grade.