Does A/C turn off automatically climbing hills ? Ford F53

I have the same problem with my 2001 Dodge Ram 1500, 360 Magnum V8.
It is NOT just a Ford problem, nor is it just an "aftermarket A/C problem.
I have seen it in many different vehicles.
If the manufacturers would have stayed with control cables (yeah, they are annoying, too, and difficult to repair) instead of vacuum motors, the problem would not exist. However, "new technology" is always better, right?

Although it's not a bad idea to turn the AC off while climbing a hill.

dougrainer wrote:

Ductape wrote:
Nonsense. Mine does not leak. Any tech worth his pay can find and fix the leak in the a/c.

Leak was a wrong choice of words. I should have stated that when the engine goes to zero vacuum, the demand on the vacuum from the After market AC systems uses up the small amount of vacuum in a few minutes. I state this from working on Dash AC motorhome systems for 36 years and after numerous various manufacturers attempting to replace actuators/hoses/vacuum reservoirs, they ALL stated, this type problem is NORMAL. If you want to eliminate the problem, you install the 12 volt vacuum pump on Gasoline Class A chassis. Even Diesel chassis's, you will get customers that come in and complain about this buzzing noise they hear while in transit for a few seconds all the time. That noise is the 12 volt vacuum pump replacing the used/lost vacuum. It runs for about 1 minute after the RV has not been driven to vacuum up the system and then runs a few seconds whenever the vacuum has dropped down. BUT, IT IS A NORMAL PROBLEM. Especially on Ford Chassis's. For the cost to use as mityvac and troublshoot the actuators and hoses to find a possible leak at a shop is way more than just purchasing a 12 volt vacuum pump and installing and eliminating the problem. Doug

dougrainer, I am not a professional RV HVAC repairman and I've never knowingly has a vehicle with an aux pump. I can see in a flash that there are assist pumps from as low as $50 to as high as $500. I do, however, have a question for you, how do you hook the pump up to the vacuum system? I see pumps with a single hose connector and some with two. I kinda figured that the one connector pump needs a tee and is between the reservoir and the HVAC selector switch, the two line, I figured was an inline and would go in the same place. Second question, there are several pumps available for Ford trucks, is there anyone better than another.

I want to file this away for future use as I have a Chevy based rig an I mine fixed and I don't have problems at this time.

TIA Dave

Not an A/V problem, but a vacuum assisted controller leak.

There is a check valve that will go bad in the line by the vacuum tank.
When there is a leak you will loose the control that keeps the air mixing door set for A/c only and bring in outside air or in case of a total loss, the system will revert back to the default setting of defrost only.

There is a present thread in the Class C here on this and non-dealer fixes.
Ford truck and van forms on the web are full of these complaints and fixes.

On a Class C the dealer wants $900 due to labor.
DYI fix as posted on the Class C forum is under $20.00 and maybe an hour time.

Everything is build with tolerances and each manufacturers have them different.
Some might remember Mercedes cars from 1970's and 1980's. They had central locking that was vacuum-operated.
Originally the system would hold the vacuum for several days, so even when you took vacations, all doors would still open without starting the engine.
Over the years the system would hold less, or call it leak more and days shrank to hours and then minutes.
Same on AC system. Well done would hold the vacuum for days, but poorly done will loose it in minutes.
When engine runs and supply unlimited vacuum, that is not a problem, but when you drive at WOT on gasser, you are not supplying vacuum and leaky flap system reverts to default what always is defrost.
Additional vacuum pump will do the trick, but that is more a bandage on leaky system.
Also think about dust entering the engine with those leaks.

The most likely cause is a leaking check valve in the vacuum supply line.

In the early 2000's this was a well know problem with F53 chassis. The fix at that time was a larger vacuum canister. I believe Ford issued a service bulletin on this issue.

Fred

Ductape wrote:
Nonsense. Mine does not leak. Any tech worth his pay can find and fix the leak in the a/c.

Leak was a wrong choice of words. I should have stated that when the engine goes to zero vacuum, the demand on the vacuum from the After market AC systems uses up the small amount of vacuum in a few minutes. I state this from working on Dash AC motorhome systems for 36 years and after numerous various manufacturers attempting to replace actuators/hoses/vacuum reservoirs, they ALL stated, this type problem is NORMAL. If you want to eliminate the problem, you install the 12 volt vacuum pump on Gasoline Class A chassis. Even Diesel chassis's, you will get customers that come in and complain about this buzzing noise they hear while in transit for a few seconds all the time. That noise is the 12 volt vacuum pump replacing the used/lost vacuum. It runs for about 1 minute after the RV has not been driven to vacuum up the system and then runs a few seconds whenever the vacuum has dropped down. BUT, IT IS A NORMAL PROBLEM. Especially on Ford Chassis's. For the cost to use as mityvac and troublshoot the actuators and hoses to find a possible leak at a shop is way more than just purchasing a 12 volt vacuum pump and installing and eliminating the problem. Doug

Ductape wrote:
Nonsense. Mine does not leak. Any tech worth his pay can find and fix the leak in the a/c.

Ductape is correct, they do not leak inherently leak.

Back in the days when I was a newby, I had the same problem with the A/C on a P32 chassis mounted MoHo. I spent a bit of money on a RV repair shop "fixing it" with absolutely no luck.

I was doing one of my infamous sit and ponder things when I decided to look into the vacuum system. Without doing a tedious step by step test description, I started with the source and tested every hose and actuator and selector switch in the HVAC's vacuum system.

I have a MiteVac hand held vacuum pump. I finally found a actuator(motor) for a door that opened and closed the inside/outside air had a hose from the plastic vacuum tube to the actuator that sorta, kinda. almost maybe fit the tube from the actuator. In other words, I found that the installer used the wrong size hose in a very inaccessible place that neither fit the plastic supply line nor the actuator.

Replaced the hose and, no more leak and therefore, no default to defrost when climbing long grades.

On most systems there is HVAC panel that usually has about 6 or 8 vacuum hoses attached to it. One hose, usually the largest, is from the reservoir and the rest are to the actuators. Vacuum test each line to and from the reservoir and the actuators until you find one that won't hold a vacuum.

When I called the shop that "fixed it", and told them that what took them a couple of weeks to fail at, I found and fixed in about three hours. I asked for the money backed that they charged for "fixing" my system because my troubleshooting durned up absolutely no evidence of any testing or repairs. There was dirt and dust on parts they suggested they had removed or replaced and tested. and finally when I told them to forget it, I would just let a Small Claims Administrative Judge decide, they returned my money. When I told the owner that I would be happy to come to his shop and without charging him a cent, teach his HVAC guy how to trouble shoot a problem like mine, he told me in some very vulgar terms to never darken his doorstep again.

Also there should be a one way check valve between the intake manifold and the vacume storage tank so that when the engine drops to 0 vaccume, you can still operate accessories providing that you don't have significant leaks