Diagnosing a HVAC vacuum issue on a Ford F53

[Mike_Schriber]

The AC/heat is switching to the defroster under higher RPM conditions on my 2006 F53 chassis Damon. It actually seems to be doing it now under low throttle steady state conditions as well. Obviously a vacuum issue but I'm not finding any obvious leaks.

The leads me to focus on the vacuum accumulator but I'm not sure how to test it. I can't even figure out how to remove the lines going in and out and I don't want to break anything fumbling around. Any suggestions?

Thanks!

Mike

[pwn]

Well, I'd like to thank JimDandyAZ for his post. It has helped me tremendously with a problem that has been plaguing me for almost two years. THANKS FOR reviving this thread and reposting this information.

[Gdetrailer]

Jeeze JimDandy, nothing like reviving a LONG DEAD thread, OP found their problem and fixed it RIGHT nearly one year ago.. AND it didn't require a bunch of hokey aftermarket parts..

[JimDandyAZ]

APDTY 015325 Vacuum Pump -... https://www.amazon.com/dp/B00BVQZSKO?ref=ppx_pop_mob_ap_share

APDTY 112687 Wiring Wire Harness... https://www.amazon.com/dp/B00UG9VZDG?ref=ppx_pop_mob_ap_share

E Support 12V 24V Standard Add A... https://www.amazon.com/dp/B0146EB8EM?ref=ppx_pop_mob_ap_share

https://www.dormanproducts.com/c-98-vacuum-

Hose from local auto store

Parts

[JimDandyAZ]

dougrainer wrote:
This is a common problem on Ford Class A chassis going back over 20 years. The ONLY sure fix is to install a 12 volt vacuum pump and plug the vacuum line from the engine. You will have people tell you to test this and test that and add another accumulator, and check all the vacuum lines and motors on the dash evap system. The plain fact is, the aftermarket Dash AC systems on Ford Class A's have inherent vacuum leaks and cannot overcome the engine going to zero vacuum on full acceleration or climbing hills. You can do a search for this problem on this forum and see all the silly things people are told to do, when the plain fact is, you need the 12 volt pump. I speak from over 38 years and still working on Motorhome Dash systems and YES, I have installed a few of the 12 volt pumps, even years ago when the Coach Maker paid for the pump installation when the RV's were under warranty. Doug

The truth was in the middle. I found a vac leak with a pump tester. And Doug Rainer was right .. the F53 dash is inherently leaky. Installed the vacuum pump Doug cites. Bought the wiring harness while only using the black and green. Tied power to an ignition- on piggyback fuse. Unit shuts off when vacuum is correct. Does not run when ignition is off due to choice of where to tap 15 amp fuse.



***Link Removed***

[kmb1966]

dougrainer wrote:
This is a common problem on Ford Class A chassis going back over 20 years. The ONLY sure fix is to install a 12 volt vacuum pump and plug the vacuum line from the engine. You will have people tell you to test this and test that and add another accumulator, and check all the vacuum lines and motors on the dash evap system. The plain fact is, the aftermarket Dash AC systems on Ford Class A's have inherent vacuum leaks and cannot overcome the engine going to zero vacuum on full acceleration or climbing hills. You can do a search for this problem on this forum and see all the silly things people are told to do, when the plain fact is, you need the 12 volt pump. I speak from over 38 years and still working on Motorhome Dash systems and YES, I have installed a few of the 12 volt pumps, even years ago when the Coach Maker paid for the pump installation when the RV's were under warranty. Doug


https://www.amazon.com/APDTY-015325-Vacuum-Pump-Supplemental/dp/B00BVQZSKO

I chased this problem down for over 10 years! Went to Ford dealers, a/c mechanics, auto mechanics, so many people looked at this problem and could not fix it for real. Finally, I took Doug's suggestion, installed the pump and problem was fixed for good.
I'd go the aux pump route as suggested. it fixed it and worked without issue after that!

[Mike_Schriber]

Wow. This got going. My issue is solved. As I posted, there was still vacuum more than a half hour after the engine was turned off so all the other lines are good and so is the accumulator. I've had an issue with this line before. It's not shielded and it's exposed to heat, etc. Looking to replace the entire thing.

I've put 50,000 miles on this rig with plenty of high throttle extended uphill running and I've never run out of vacuum. YMMV.

Mike

[JaxDad]

wolfe10 wrote:
Doug's answer IS spot on for any driver of a gasoline powered vehicle who expects adequate vacuum to operate the dash HVAC system under heavy load= low engine vacuum. Suspect a number are fit after a first drive in real mountains where sustained high throttle/low vacuum conditions are encountered.

No question, it will not magically fix other leaks in the system if they are large enough to overcome the supplemental pump.

BTW, that is the standard vacuum pump on a large number of diesel vehicles, since diesel engines have no vacuum. VERY common pump.

And yet those smarty-pants engineers with the coke bottle-bottom glasses and pocket protectors found it entirely adequate to just add a big vacuum accumulator to the system and all is good.....

Unless you have a mechanic who’d rather throw parts at the vehicle instead of actually fixing the problem.......

As a wing-wiper I served with used to say, “maintain it, or you’re in for a looooong walk home.’”

[Pirate1]

Look for this vacuum reservoir under/near the front right area. They have a tendancy to implode near the plastic welds. It will impact your ac controls.

[westend]

The leads me to focus on the vacuum accumulator but I'm not sure how to test it. I can't even figure out how to remove the lines going in and out and I don't want to break anything fumbling around. Any suggestions?

As was posted, using an accelerant next to the vacuum hoses is an old school diagnostic technique. I've used ether (starting fluid) for this as I usually have a can of it in the shop.

[wolfe10]

Doug's answer IS spot on for any driver of a gasoline powered vehicle who expects adequate vacuum to operate the dash HVAC system under heavy load= low engine vacuum. Suspect a number are fit after a first drive in real mountains where sustained high throttle/low vacuum conditions are encountered.

No question, it will not magically fix other leaks in the system if they are large enough to overcome the supplemental pump.

BTW, that is the standard vacuum pump on a large number of diesel vehicles, since diesel engines have no vacuum. VERY common pump.

[JaxDad]

dougrainer wrote:

JaxDad wrote:
Glad you found the actual problem instead of just throwing silly wasted parts at it.

So much for the “ONLY” solution........

The main reason I won’t go to the stealerships is for exactly that reason, there’s no THINKING about the problem and finding the solution, it’s just throwing parts at it because a book or computer said to do that.

Thankfully the only place where such foolishness does NOT exist is in aviation, which given the price of parts is a VERY good thing.

According to the description the OP made, Heavy acceleration, The problem was the vacuum was used up......

Doug

And yet the OP’s post actually said;

Mike Schriber wrote:
It actually seems to be doing it now under low throttle steady state conditions as well. Obviously a vacuum issue but I'm not finding any obvious leaks.

Mike

BTW, my problem stealerships is NOT ‘trust’, it’s the SA and guys in the shop who just throw parts at things because they walk up to the vehicle with a preconceived ‘knowledge’ of what the problem MUST be instead of actually diagnosing the problem and fixing THAT.

In this case a 12 volt electric vacuum pump would have done ZERO unless it happened to be spliced in where the leak was by complete fluke.

There’s no savings in doing a job ‘fast’ if the problem isn’t fixed or an expensive ‘repair’ that was NOT needed is done instead of the repair.

I found my vacuum leak in about ONE minute using a propane bottle, my repair also ‘cost’ me about 2 feet of rubber vacuum tube, maybe a dollar.

Can you sell and install a 12 volt vacuum pump for ONE dollar?

[Gdetrailer]

dougrainer wrote:

JaxDad wrote:
Glad you found the actual problem instead of just throwing silly wasted parts at it.

So much for the “ONLY” solution........

The main reason I won’t go to the stealerships is for exactly that reason, there’s no THINKING about the problem and finding the solution, it’s just throwing parts at it because a book or computer said to do that.

Thankfully the only place where such foolishness does NOT exist is in aviation, which given the price of parts is a VERY good thing.

According to the description the OP made, Heavy acceleration, The problem was the vacuum was used up, which IS a common problem on Ford Chassis vacuum supply. The difference is YOU don't trust dealerships, that is fine. But you come to me and then you pay me $150 an hour to find a supposed vacuum leak, then I find some leak and fix it $300 later. Then you come back and tell me the problem still happens on full acceleration, you then pay me MORE. So, a customer comes to me and based on MY EXPERIANCE, I charge him $150 install plus the $75 for the Vacuum pump and at $225, he is fixed EVEN IF HE HAS A SMALL VACUUM LEAK. The 12 volt pump will overcome any supposed vacuum leak. Lets wait and see if the OP's problem is fixed on heavy acceleration. Doug

Doug, your thinking on how to "diagnose and fix" IS exactly the way most all "dealerships" approach repairs now days.

It IS quick and fast and the dealership EARNS the money in a hurry.

They don't have REAL troubleshooting and diagnostics training which leads to mickeymouse fixes and just throwing parts at it.

All the time not fixing the real problem, only masking the problem and often ADDING NEW PROBLEMS.

Yeah, I am angry with how repairs went with one of my vehicles, cost me nearly $4K, ten trips later and they NEVER fixed the problem.

I ended up doing Internet searches and FOUND the fix, a can of carb cleaner and a rag.. Instead I ended up paying for new fuel pump, new filter, new plugs, new cat.. Then down the road because of other problems I ended up having to change all the O2 sensors which were damaged and finally the other cat which because the dealer didn't fix but add other problems..

Yeah, $4K and dozens of trips to dealer, lost use of that vehicle for months, couldn't depend on it...

[RLS7201]

JaxDad wrote:
Take a small propane torch and unscrew the head leaving just the valve and pipe, then slip a piece of tubing over the end of the pipe. With the engine idling and the valve on the torch open (but not lit obviously) run the end of tube along every vacuum tube in the HVC system.

When you get to the vacuum leak the engine will inhale the propane and the extra ‘fuel’ will cause the engine to speed up a little, when you pull it away it goes back down again.

It makes finding vacuum leaks super easy.

I've been around the auto repair industry over 55 years and just learned another trick to add to my repertoire. Thanks for posting.
With this trick, I'll bet even Doug will consider looking for leaks.

Richard

[dougrainer]

JaxDad wrote:
Glad you found the actual problem instead of just throwing silly wasted parts at it.

So much for the “ONLY” solution........

The main reason I won’t go to the stealerships is for exactly that reason, there’s no THINKING about the problem and finding the solution, it’s just throwing parts at it because a book or computer said to do that.

Thankfully the only place where such foolishness does NOT exist is in aviation, which given the price of parts is a VERY good thing.

According to the description the OP made, Heavy acceleration, The problem was the vacuum was used up, which IS a common problem on Ford Chassis vacuum supply. The difference is YOU don't trust dealerships, that is fine. But you come to me and then you pay me $150 an hour to find a supposed vacuum leak, then I find some leak and fix it $300 later. Then you come back and tell me the problem still happens on full acceleration, you then pay me MORE. So, a customer comes to me and based on MY EXPERIANCE, I charge him $150 install plus the $75 for the Vacuum pump and at $225, he is fixed EVEN IF HE HAS A SMALL VACUUM LEAK. The 12 volt pump will overcome any supposed vacuum leak. Lets wait and see if the OP's problem is fixed on heavy acceleration. Doug