Vacuum loss going up hills

I have a '95 Town car that has great a/c, except for when going up hills it shuts down. As soon as I take my foot off the gas, it comes roaring back.

I've checked the vacuum storage canister (black plastic box) on the left fender well, and it's o.k.
I've checked all the red, blue, green, yellow vacuum lines @ the heater control and the various bellows that they control for scrapes/ kinks and they all hold vacuum/pressure.
I've checked the main vacuum line coming out of the elbow behind the throttle body and it is new and o.k.

I occasionally get the infamous "low flow egr" code, but I think this is due to loss of vacuum that is required to hold it open. The egr is brand new, as is the pipe to the right bank exhaust pipe and we have 4 new o2 sensors installed too. Also the horse shoe shaped passage under the intake manifold elbow is squeaky clean.

Any other ideas would be welcome.........

Thanks,
Mike in Colorado

I would inspect the remaining vacuum hoses at the firewall as well as the pcv valve hose, all these can cause a loss of vacuum.

For the EGR seems like you've checked everything other than the DPFE sensor and the EVR.

The dpfe is attached to the intake elbow and has two black hoses running to the exhaust pipe of the egr valve. Make sure all these hoses are ok and correctly attached.

The evr is also attached to the elbow at the passenger side and has a red and a green hose. Remove the upper cap being careful not to break it to reveal the filter. Clean this one with mild soap and water, let it dry and finally clean the evr case with a wet cloth.

Oscar.

A smoke test will pinpoint any vacuum leaks.

Insufficient flow to egr, is probably because of blocked egr gas passages on your Intake.

I wonder if there is some moisture sitting in one of the lines, and the change in angle as you go up a hill is enough for it run together and cause a problem?

I would inspect the remaining vacuum hoses at the firewall as well as the pcv valve hose, all these can cause a loss of vacuum.

For the EGR seems like you've checked everything other than the DPFE sensor and the EVR.

The dpfe is attached to the intake elbow and has two black hoses running to the exhaust pipe of the egr valve. Make sure all these hoses are ok and correctly attached.

The evr is also attached to the elbow at the passenger side and has a red and a green hose. Remove the upper cap being careful not to break it to reveal the filter. Clean this one with mild soap and water, let it dry and finally clean the evr case with a wet cloth.

Oscar.
Oscar,
Thanks for the leads.
I cleaned the foam filter @ the top of the EVR this a.m.
Yes, the two black hoses that run from the DPFE to the EGR feed pipe are in good shape and hooked up properly The ones w/ the orange centers.

Question, There are 2 vacuum lines that run thru the firewall. the small black one seems to "power" all the a/c, vent/ heater controls on the dash.
The larger white one runs someplace up the steering column and then a smaller white one comes back down and goes to a bellows on the emergency brake.
They appear to be separate systems coming from a "distribution block" mounted on the firewall behind the EVR.
What stumps me is the power brake system, which relies on vacuum, seems to be unaffected by all this.
Mike

Oscar,
What stumps me is the power brake system, which relies on vacuum, seems to be unaffected by all this.
Mike

The brake booster should be feed from a separate, and dedicated line off the manifold.

You're welcome!

The brake system is unaffected because it also has a small reserve in the booster and a check valve on it; it is the big plug that attaches to the booster unit.

The 2 vacuum lines are the AC control vacuum and the emergency brake automatic release lines (you know the e-brake is released when you put the car on D).

Since you mention you have checked the remaining components and they are OK I would think the check valve on top of the vacuum "distribution block" (also called vacuum distribution tree) has gone bad, it should be easily available at most autoparts stores.

To check it remove the two parallel lines at the top of it (one at a time) with the engine running and check for vacuum. If you are getting vacuum on both lines the next step will be to connect a 'T' fitting to both lines and pump 15 inches (maximum) of vacuum. If the vacuum loss is bigger than 1 inch per minute the check valve is bad.

Good luck,

Oscar.

Oscar,
Thanks for the "lead" about the check valve. I'll do your test this afternoon.
Can you tell me how to remove the check valve from the "tree" without breaking the tree. If I break it, it's going to be a nightmare reconnecting the vacuum lines to the new one.
Mike

Thant's why a smoke test is better!

Oscar,
Thanks for the "lead" about the check valve. I'll do your test this afternoon.
Can you tell me how to remove the check valve from the "tree" without breaking the tree. If I break it, it's going to be a nightmare reconnecting the vacuum lines to the new one.
Mike

To be honest I don't know if the check valve can be removed alone in our model, I knowsome models had it integrated to the tree and some others didn't. If you have problems with available space you can always remove the cowl under the wipers, it will take about 15 minutes but you'll have LOTS of space.

Thant's why a smoke test is better!

The smoke test is a great idea, but will only show leaking points and no defective components like the check valve.

Oscar.

oscar,
The check valve @ the top of the distribution tree just plugs in w/ a rubber tube that fits into the body of the tree.
I found a generic replacement @ NAPA for $6.50 and pluged it in.
Now I get a/c thru the floor and defroster vents, but not thru the dash vents.
Got to go back in and check all the tubes under the dash.
I knew I should not have put it all back together before I tried it.
Mike

If that's the only thing you disconnected then your problem lies there, one of the lines either is not properly seated/disconnected or got cracked during the process.

When there is no vacuum to the dahsboard the system defaults back to defrost mode to prevent your windshield to become foggy should you have a vacuum delivery problem.

Oscar.

If that's the only thing you disconnected then your problem lies there, one of the lines either is not properly seated/disconnected or got cracked during the process.

When there is no vacuum to the dahsboard the system defaults back to defrost mode to prevent your windshield to become foggy should you have a vacuum delivery problem.

Oscar.
Oscar,
The NAPA generic replacement did not work, as the 2 barbs for the vacuum tank and the feed to the htr/ac controls were not big enough to seal on the lines.
I ordered a ford part from my local dealer today. $ 8.00 total cost.
I'll put it in on Friday. For now the old part is back in. It has a short piece of rubber tube on the bottom barb and just pops into the top of the tree.
Will let you know how the new one works next week, after a road trip to Denver and back.
Mike

Oscar,
The NAPA generic replacement did not work, as the 2 barbs for the vacuum tank and the feed to the htr/ac controls were not big enough to seal on the lines.
I ordered a ford part from my local dealer today. $ 8.00 total cost.
I'll put it in on Friday. For now the old part is back in. It has a short piece of rubber tube on the bottom barb and just pops into the top of the tree.
Will let you know how the new one works next week, after a road trip to Denver and back.
Mike

New info,
I replaced the one way valve @ the top of the "tree" this p.m. w/ the official ford part.
Started her up, and here's what happened.

With the htr/ac system off, and the car idling, I turned the system on by pushung the "vent" button , and got air from the 4 dash vents.

Then I pushed the "floor" button and got air from the floor and defroster.

Then I pushed the "vent" button again and the system WOULD NOT go back to blowing air out the vents.

However when I turned the system off, I could get air from the vents again by hitting the "vent" button.

I have not tested her on any hills yet to see if it still defaults to floor/defrost on a long pull. But I have a hunch it will.

Very perplexing ???????????
Mike
:confused::confused::confused:

Hi Mike,

Hmmm that sounds weird. I would think maybe something is causing the deflectors not to properly return to their positions, perhaps low vacuum coming from the engine??

I would try the guide in the following link and see if anything comes up:

http://www.lincolnsonline.com/tech/00128.html

Oscar.

Hi Mike,

Hmmm that sounds weird. I would think maybe something is causing the deflectors not to properly return to their positions, perhaps low vacuum coming from the engine??

I would try the guide in the following link and see if anything comes up:

http://www.lincolnsonline.com/tech/00128.html

Oscar.

Oscar,
Well it's been a while since I posted, but after a 500+ mile trip w/ all the same symptoms, I decided to try out my new vacuum pump (thanks to harbor freight).
I pulled the black feed line loose from the Vacuum junction block just behind the ash tray, to see if the one way valve, vacuum tank and feed line to the heater control would hold 15 mm/Hg = yep she holds.

Then I pulled the same vacuum on each individual control actuator. Yellow and blue are right behind the ashtray (which comes out w/ 2 screws), All actuators held @ 15. I thought it might be the blue one, since that's the actuator that switches between vent and floor, but she held.

Next I pulled the heater control unit (4 screws) and removed the 2 nuts holding the vacuum "harness" to the back of the unit w / a "gummy bear plug" and rechecked all the lines = o.k.

Next I pulled a vacuum on the center feed line going into the heater control unit P/N PMF5VH-19C933-AF (1995 EATC FN116/EN114). What do you know, pumped her up to 15 and she SLOWLY decayed to O.

Took the unit apart and there are 4 solenoids working on a black plastic valve body. This cannot be disassembled without ruining it. The actual solenoid assy carries Federal Mogul #F4LF-19D611-AA. I'll bet you a dollar to a donut, my friendly Ford dealer won't sell me just the controller. I'll bet I have to buy the whole shebang !!!!!!!

So that's my tale. Now the search begins for the part.

Best Regards,
Mike in Colorado
:runaround::runaround::runaround:

Good job on finding the problem!

Shows the value of having the right tool and following a methodical approach.

I still can't believe that the US car makers are still using Vacuum for actuators.
This is technology from the 50s that the rest of the world dropped in the 70s because it was unreliable, and problems are hard to diagnose.

Good job on finding the problem!

Shows the value of having the right tool and following a methodical approach.

I still can't believe that the US car makers are still using Vacuum for actuators.
This is technology from the 50s that the rest of the world dropped in the 70s because it was unreliable, and problems are hard to diagnose.


Moppie,
A bit of good news to add here. After my local ford dealer told me this morning that my control unit had been superceeded by another number, THAT IS NO LONGER AVAILABLE (?), I found on e-bay a fellow in California that rebuilds these control units (with something better inside), and guarantees them for life, @ a cost of $189.00 (us) on an exchange basis.
I think this beats buying a salvaged unit that may have the same issue later on.
Question, has anyone had experience any "rebuilder" they would like to comment on.
Best Regards,
Mike
:uhoh::uhoh::uhoh:

It´s good to know you have found the problem.

I know a there's a guy in the forum who rebuilds these units and I know from other users experience he is good, you should try emailing him with the next link

KITT1993 (http://www.automotiveforums.com/vbulletin/member.php?u=540316)

and clicking on the "contact info" button

Hope you get a good deal!

Oscar.

I'm posting a final note on this subject just to close out the thread.
I did purchase a reconditioned heater/ac control unit from Module Repair Pro Inc in L.A. Calif. Ph 818-429-4889. Cost was $289.00 w/ a $100.00 refund when your core is returned. I did mine thru Paypal from his e-bay site. One trip to Salt Lake City and one trip to Cheyene Wy. from our Colorado base, and all is fine....
Note: his condition of sale is that there are "sealing" tapes on his units which are "guaranteed" for life, and if you open up the unit and break the tapes, it voids the guarantee. Thanks to a dental mirror and a bright lite I was able to confirm that the Federal Mogul unit had been replaced. I wonder where a person would find these ????? It's an easy thing to do replace....
Best regards to all,
Mike in Colorado