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#4103792 - 04/02/21 02:57 PM 1996 P71 A/C not cooling - comp okay fluid okay?
triplej057 Offline
n00b

Registered: 10/30/12
Posts: 44
Loc: California
Hello,
The AC finally went out on the 1996 P71 - the compressor DOES engage fine, and the low-side port indicates fluid is full / charged.

The evap cylinder gets cool, but not cold, and no "sweat" on it or on the lines.

I did look around, but most all posts center on non-functional compressors ...

Any help would be greatly appreciated,
Thanks as usual, CrownVic.net members,
Dave

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#4103796 - 04/02/21 03:00 PM Re: 1996 P71 A/C not cooling - comp okay fluid okay? [Re: triplej057]
triplej057 Offline
n00b

Registered: 10/30/12
Posts: 44
Loc: California
To add, don't think it can be the blend door, because heat is nice and hot on red, and air is "room temperature" on blue - so the blend seems to be functioning along with the blower motor, etc.

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#4103802 - 04/02/21 03:45 PM Re: 1996 P71 A/C not cooling - comp okay fluid okay? [Re: triplej057]
Old_Guy_Stu Offline

Over the Hill

Registered: 04/28/19
Posts: 2068
Loc: Cleveland, OH
When the compressor engages, how long does it stay on? If it's just a couple seconds, you probably need to top up. Ideally you'd check with a proper manifold gauge to check both high- and low-side pressures.
_________________________

1988 CVLX Formal Roof (Love Boat) POTM July 2019 & Aug 2020, 55K
E-code lights w/ relays, LEDs w/ switchbacks, 15x8 Ansen slots w/ 255/60 BFG's, Kenwood stereo, various hacks.
1988 CVLX (Destroyer) 1998-2001 driven to death 202K
1988 Squire (Chris Craft) 1996-1998 junkyard rescue driven to death 199K

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#4103904 - 04/04/21 12:19 AM Re: 1996 P71 A/C not cooling - comp okay fluid okay? [Re: triplej057]
triplej057 Offline
n00b

Registered: 10/30/12
Posts: 44
Loc: California
Thanks for the reply - it was very intermittent, like a few seconds, but after "reading the pressure" with one of those cheap gauges from the auto parts store, it runs all the time now (never cycles off because it never gets cool, as far as I can tell) - I did try a small shot on the low pressure port but no change. Maybe something has failed on the high pressure side? I'm just very nervous adding too much when the low pressure side is "in the green".

Thanks for any additional advice

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#4103906 - 04/04/21 12:26 AM Re: 1996 P71 A/C not cooling - comp okay fluid okay? [Re: triplej057]
triplej057 Offline
n00b

Registered: 10/30/12
Posts: 44
Loc: California
To clarify, the compressor does turn off when I change the mode, but on AC mode, it seems to run constantly, but air never gets cool.

Thanks

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#4103914 - 04/04/21 07:52 AM Re: 1996 P71 A/C not cooling - comp okay fluid okay? [Re: triplej057]
Old_Guy_Stu Offline

Over the Hill

Registered: 04/28/19
Posts: 2068
Loc: Cleveland, OH
You really need a proper manifold gauge to see what's going on. Check high side and low side. Lots of good info here:
https://www.slideshare.net/abrahamjospher/automotiveairconditioningtrainingmanual
All I can say for sure is, there's a problem.
_________________________

1988 CVLX Formal Roof (Love Boat) POTM July 2019 & Aug 2020, 55K
E-code lights w/ relays, LEDs w/ switchbacks, 15x8 Ansen slots w/ 255/60 BFG's, Kenwood stereo, various hacks.
1988 CVLX (Destroyer) 1998-2001 driven to death 202K
1988 Squire (Chris Craft) 1996-1998 junkyard rescue driven to death 199K

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#4103934 - 04/04/21 08:59 AM Re: 1996 P71 A/C not cooling - comp okay fluid okay? [Re: triplej057]
Rootintootin Online   content
Climber

Registered: 02/26/08
Posts: 621
Loc: North Carolina
WooHoo. Ding, ding, ding. First a/c post of the new spring season.

First, when was the last time any work was done on the a/c, if any?

What is the ambient temperature where you are working on the a/c? There are charts all over the internet that tell you how long it should be on, off according to what the local temperature is. The higher the ambient temp, the longer the compressor should be running. When it gets into the 80's, it might not ever shut off on a properly charged system.

That evap cylinder is called the receiver/dryer. After the refrigerant has done it's thing inside the cabin, it gets pulled by the compressor into receiver dryer where any moisture gets separated out before going on to the compressor. You can't compress a liquid.

When using heat, can you move the air around to all outlets? Windshield, dash registers, and floor?

This whole a/c thing is based off temperatures and pressures. It doesn't cycle off because it gets cool. The switch that controls cycling operates within a certain pressure range. It controls when electricity goes to the switch that engages the field coil that engages the clutch is turned on and off. You need actual numbers, not guesses or feels likes.

Nothing personal, I'm not picking on you, but unless you are going to school yourself and invest in at least a minimum of tools to do this right, you would be better off finding a competent shop to at least diagnose the problem. It's too easy to screw something up that would be any easy fix. When the operation started out being "very intermittent" and after "reading the pressure" it stays on all the time indicates you might have messed up something that was OK before.

When you did your "small shot" you probably didn't get anything in. Bet you didn't know, but just sitting there and not even running, there should be 60-80 psig in the system. That's called the static pressure. If you don't have that, you're already wrong before putting the low side gauge on to see if it's in the green. That green means the low side is operating within a range of about 22 psig up to about 50 psig. None of this gives you any idea about what is happening on the high side.

All indications are you've had a slow degradation in the system over a number of years, which is normal. Over the last winter, enough refrigerant leaked out past old weak o ring seals or finally migrated out through old hoses that there isn't enough to operate properly. Topping it off might give you some more time. but if it leaked out, anything you could put in would just leak out again until you fix the source of the leak.

Now, if you use some actual gauges to get the real numbers, you might find my whole post has been nothing but a pile of poop.
_________________________
97 CVPI, 142K miles, small trans fluid leak from front seal area, water leaks to inside from evaporator housing and drivers side A pillar, cold weather glitch with wiper motor, headliner covering starting to flake off, tear in drivers seat bottom. Flickering, blinking radio display, What's next?

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#4103978 - 04/04/21 08:37 PM Re: 1996 P71 A/C not cooling - comp okay fluid okay? [Re: triplej057]
TheShadow Offline

Over the Hill

Registered: 05/01/07
Posts: 1734
Loc: SoCal High Desert
All of the above.

In a system with very slow leakage/seepage, the leaking refrigerant will be replaced by atmospheric air. A very quick (and dirty/frowned upon) test of whether any refrigerant is still in the system would be to depress the Schrader valve and let a small amount of gas to escape. If the temperature of the gas is more like room temp, there is very little, if any, refrigerant. If the temperature is very cold, the charge is ok, and your problem lies somewhere else.

If you do the above, be aware that refrigerant get extremely cold, and can cause frostbite, so wear gloves or wash hands immediately after.
_________________________
'95 P71, 5xx,xxx miles, Rebuilt tranny, 2.73. Lives as a cab, and will die as a cab. (Died-FrontEnder)
'96 P71, 640,xxx on original drivetrain. (Now parts car - T-bone & roll)(You should see the roof - A,B & C-pillars chopped on driver side)
New to list: '96 MGM (Nice! @ 35x,xxx), '97 CV P71, '98 CV P71, '00 CV P71, 01 P71 (2 of 'em) '03 CV P71 (Nice so far) (All Ford Zinc Yellow w/Black decals & trim) And the list is growing...........
Taxicab mechanic: I HATE DRIVERS!

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#4103982 - 04/04/21 08:58 PM Re: 1996 P71 A/C not cooling - comp okay fluid okay? [Re: triplej057]
TheCableGuy Offline
Climber

Registered: 04/08/19
Posts: 963
Loc: Far Northwest AZ
Not that any of this matters.. but I had AC issues last summer. Usually how these things go.

If the car was idling for more than an hour just sitting, the rpms would just start surging, from 600 to 1200(when compressor clutch would engage etc), up and down, when it was 118 outside. AC temp started getting really humid quick.

Took it to a friend of mine who is a Ford tech. Trying to remember exactly but he said I had a bad shrader valve and it was leaking just a little. So he replaced that, changed this weird filter looking thingy and did a full vacuum and recharge.

He said if I still have weird AC issues, to replace the condenser because he also thinks there is a blockage of some sort in it. The pressures were still a little high after all he did; but he did say that there is no handbook when you get over 100 degrees outside.

So it’s been 95 already and my AC seems fine for now... still haven’t replaced the condenser. Usually blows at about 55-60 when idling and 45-50 when driving on the highway.
_________________________
2010 P7B 150K. 11K hours. 3.27, RKE, Cruise, Ported stock plenum, JMod
2011 Sierra 1500 155K, too many mods to list. (RIP 01-05-2019)
2001 Durango R/T 5.9. 230K. SOLD 5-1-19

I’m a classical textbook over-thinker.


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#4104458 - 04/08/21 03:08 PM Re: 1996 P71 A/C not cooling - comp okay fluid okay? [Re: triplej057]
triplej057 Offline
n00b

Registered: 10/30/12
Posts: 44
Loc: California
Thanks for the replies! I really appreciate it - sorry for the slow response but so many projects, and work, family, etc.

To answer some of the questions:
The A/C has never been serviced - I've owned the car for 20 years and the A/C has worked perfectly since the day that I bought it in late 2000 - why would it stop working now? Hahaha JK!

Depressing the shrader valve there is some green leakage (the dye) so it definitely has some refrigerant in there. I charged it with a whole can of "A/C Pro" (the larger black one) and that seemed to help a bit, but it still only gets cool, not cold, and the compressor runs all the time as far as I can tell, never cycles off. Also sometimes it still exhibits the original symptoms of simply not wanting to get cool at all (failed system) even though we know that the compressor is running and it is "full" of refrigerant.

Outside temperature is 80's in California right now - and also yes, I can send the heat to different locations - Dash, floor, etc.

@Old_Guy_Stu - thanks for the link on general A/C information, lots of good info in there, I've read it, but I'll re-read it soon.

I understand that it is a precise process and at this point needs a precise diagnosis - I'll get some manifold gauges online, but where is the high pressure service port to connect them? I've looked around, but haven't been able to find that answer for a 1996 P71 ... ? And do I just plug them in, just like the low side? Or is there some extra procedure / danger because it's the high pressure port? Most service manuals that I've read just say "connect your gauges to the service ports" or similar ...

Thanks for the advice! It is an older vehicle, a bit of a beater, although I still love her, but she's been to hell and back - 208K miles! That being said, I do not want to dump too much money into her right now with professional A/C restoration, etc. which is why I am asking here - my 2009 P71 is my main ride - but the 1996 P71 is a nice backup vehicle.

Thanks again,
Dave


Edited by triplej057 (04/08/21 03:13 PM)

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#4104474 - 04/08/21 06:15 PM Re: 1996 P71 A/C not cooling - comp okay fluid okay? [Re: triplej057]
Rootintootin Online   content
Climber

Registered: 02/26/08
Posts: 621
Loc: North Carolina
I was looking through my old posts and found my a/c episode. I thought it was from 2013, but it went back another 2 years. I haven't had to do anything since, and I'm still getting low 30s when called for. But since it has been 10 years now, I know my day is coming for chapter 2.

https://www.crownvic.net/ubbthreads/ubbthreads.php?ubb=showflat&Number=2263050&page=1

You might be able to glean some useful info from it. Also, there is at least a ton of info to search for on the site. And don't forget to look through the BOK.
_________________________
97 CVPI, 142K miles, small trans fluid leak from front seal area, water leaks to inside from evaporator housing and drivers side A pillar, cold weather glitch with wiper motor, headliner covering starting to flake off, tear in drivers seat bottom. Flickering, blinking radio display, What's next?

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#4104506 - 04/08/21 08:52 PM Re: 1996 P71 A/C not cooling - comp okay fluid okay? [Re: triplej057]
Old_Guy_Stu Offline

Over the Hill

Registered: 04/28/19
Posts: 2068
Loc: Cleveland, OH
Originally Posted By triplej057

@Old_Guy_Stu - but where is the high pressure service port to connect them?


It's on the high-pressure line, usually near the compressor or line muffler. Should have a red screw cap (blue for low side). It should be in an obvious and easily accessible location; even Ford knows AC systems need service. To connect the manifold, it's just like the low side. Make sure all the valves on the manifold are closed first. You're looking for the high side to read about 5 times what the low side does. Actual numbers depends on outside temp.
_________________________

1988 CVLX Formal Roof (Love Boat) POTM July 2019 & Aug 2020, 55K
E-code lights w/ relays, LEDs w/ switchbacks, 15x8 Ansen slots w/ 255/60 BFG's, Kenwood stereo, various hacks.
1988 CVLX (Destroyer) 1998-2001 driven to death 202K
1988 Squire (Chris Craft) 1996-1998 junkyard rescue driven to death 199K

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