AC compressor relief valve - Diesel Forum - TheDieselStop.com
Ford Diesel Forum / Powerstroke Forum
Ford Diesel Forum / Powerstroke Forum
Go Back   Diesel Forum - TheDieselStop.com > 2008-2010 Ford Super Duties > 6.4L Power Stroke Engine and Drivetrain

6.4L Power Stroke Engine and Drivetrain Discussion of the 6.4L Power Stroke diesel engine and drivetrain in the 2008-Up Super Duty trucks. No gas engine discussion allowed except on transmissions and drivetrain that pertain to all models. Please confine discussion of topics in this forum to those items that are specific to the 6.4L Power Stroke engine.

TheDieselstop.com is the premier Diesel Truck Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools Display Modes
Old 07-10-2012, 09:50 AM   #1 (permalink)
Senior Member
 
Join Date: Jan 2005
Location: South La
Posts: 147
My Photos: (0)
Feedback Score: 0 reviews
AC compressor relief valve

My boss's truck, '09 F-250... he's having problems with some kind of relief valve relieving freon from the system. Changed the relief valve with no results... seems as if it's doing what it's supposed to do and relieving excess pressure. Any ideas why?
__________________
2014 F-350 Platinum SRW LB Ruby Red Metallic

2000 F-250 Lariat PSD 4X4 Auto CC SB 350,xxx miles, 4" Super-Lift/Fierce Attitude M/T LT31575R16's
Tymar intake, 4" turbo back MBRP exhaust, AIH delete, AC mod, ISSPRO gauges, PHP HYDRA, FFD Single Shot Stage 1's, FrX, Hutch/Harpoon Mods, Monsterbox Tranny, Tru-Cool Max

AE in Lafayette, La vicinity...
bmcnabb02 is offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 07-10-2012, 10:12 AM   #2 (permalink)
Senior Member
 
chuckster57's Avatar
 
Join Date: Apr 2008
Location: Central Valley, Ca.
Posts: 15,596
My Photos: (7)
Feedback Score: 1 reviews
There is no "pressure relief valve" on an Auto A/C system. There is a low side switch and maybe a high side switch. Both of these are screwed onto threaded ports on the refrigerant lines. There should be an O ring that seals them so refrigerant doesn't vent to the air ( Leak). I would be looking for a missing O ring first, and then possibly a bad switch.
__________________
1994 F-350 7.3 IDI Turbo, crew cab, E4OD,4:10 L/S, LB, Dually Photos
ATS Turbo upgrades: 3" DP with 3" exhaust Magnaflow XL muffler: Pictures Here
2012 Copper Canyon 273 FWRET w/2 slides, Air Lift 5000 bags
Pillar pod: Autometer C2 Series gauges: pyro,trans, boost, water, oil pressure
Hypermax Cowl induction, K&N air filter, flex-a-lite 26K trans cooler with fan,Tekonsha prodigy
Train Horns: Pictures here

PM please not visitor message
chuckster57 is offline   Reply With Quote Quick reply to this message
Old 07-10-2012, 10:27 AM   #3 (permalink)
Senior Member
 
Join Date: Jan 2005
Location: South La
Posts: 147
My Photos: (0)
Feedback Score: 0 reviews
Then what's this?

2009 FORD F-250 SUPER DUTY Parts - Tousley Ford Parts Depot
__________________
2014 F-350 Platinum SRW LB Ruby Red Metallic

2000 F-250 Lariat PSD 4X4 Auto CC SB 350,xxx miles, 4" Super-Lift/Fierce Attitude M/T LT31575R16's
Tymar intake, 4" turbo back MBRP exhaust, AIH delete, AC mod, ISSPRO gauges, PHP HYDRA, FFD Single Shot Stage 1's, FrX, Hutch/Harpoon Mods, Monsterbox Tranny, Tru-Cool Max

AE in Lafayette, La vicinity...
bmcnabb02 is offline   Reply With Quote Quick reply to this message
Old 07-10-2012, 10:38 AM   #4 (permalink)
Senior Member
 
fireguywtc's Avatar
 
Join Date: Jun 2008
Location: central tx
Posts: 539
My Photos: (4)
Feedback Score: 0 reviews
it maybe a pressure relief valve of some sort, but it is NOT venting into the atmosphere. There must be a leak somewhere else.
__________________
2012 F350 Lariat ultimate 6.7 PSD LB CC SRW Fx4,
67 F-250 Project truck, currently in a billion pieces
70 F-250 4x4 (highboy)
Past trucks: 07 F-350 xlt 6.0 PSD LB CC SRW 4x4, black on tan, A/T, 5" exhaust w/4" downpipe, SCT livewire Traded in 04 F-250 xlt 6.0 PSD SB extcab 4x4, 6spd, all stock and 97 F-250HD xlt 7.3 PSD extcab LB 4x4, 5spd, Superchips tuner, 4" turbo back exaust, K&N CAI, 02 intercooler installed, Sold
fireguywtc is offline   Reply With Quote Quick reply to this message
Old 07-10-2012, 10:54 AM   #5 (permalink)
RT
Lifetime Supporting Member
Lifetime Supporting Member
 
RT's Avatar
 
Join Date: Dec 2009
Location: Texas
Posts: 9,968
My Photos: (0)
Feedback Score: 0 reviews
There are pressure relief valves - always on the high pressure side - some models have them on the low pressure side as well. Here's a glossary site for those interested - A/C MOBILE

The two reasons most people wouldn't be aware of these is that there is a high pressure switch that should shut the compressor off before pressures reach the point where the valve would blow. The second reason (my opinion) that people wouldn't want to believe these things exist is why would you vent the freon after everything people do to prevent venting freon. Its a safety device - nothing more.

Now the question becomes - why would this thing be leaking? Especially a second one. It would have to be either a defective valve, a defective installation (or something wrong with the mount), or something causing these uber-high pressures to be realized. Before the OP's boss goes and just throws another one on, someone needs to do some real diagnostics to find out why the pressures are getting that high (if that is indeed why it is leaking). I would suggest starting with some dye and getting some good pressure readings. Make sure the valve is leaking from the relief port and not from the o-ring.
__________________
2003 F-250 XLT Crew Cab 7.3L, Chrome BigTex Grille Guard, Quad pillar - 3 ISSPRO gauges (trans, pyro, boost) and DP-Tuner F6; Roush fuel pressure / temperature / oil pressure gauges, Ford Severe Duty AIS, 31 row 6.0 transmission cooler, ScanGauge II, Marinco mod, Walker BTM
RT is offline   Reply With Quote Quick reply to this message
Old 07-10-2012, 11:32 AM   #6 (permalink)
Senior Member
 
chuckster57's Avatar
 
Join Date: Apr 2008
Location: Central Valley, Ca.
Posts: 15,596
My Photos: (7)
Feedback Score: 1 reviews
Quote:
There are pressure relief valves - always on the high pressure side - some models have them on the low pressure side as well
I guess I learned that today
__________________
1994 F-350 7.3 IDI Turbo, crew cab, E4OD,4:10 L/S, LB, Dually Photos
ATS Turbo upgrades: 3" DP with 3" exhaust Magnaflow XL muffler: Pictures Here
2012 Copper Canyon 273 FWRET w/2 slides, Air Lift 5000 bags
Pillar pod: Autometer C2 Series gauges: pyro,trans, boost, water, oil pressure
Hypermax Cowl induction, K&N air filter, flex-a-lite 26K trans cooler with fan,Tekonsha prodigy
Train Horns: Pictures here

PM please not visitor message
chuckster57 is offline   Reply With Quote Quick reply to this message
Old 07-10-2012, 02:08 PM   #7 (permalink)
Senior Member
 
fireguywtc's Avatar
 
Join Date: Jun 2008
Location: central tx
Posts: 539
My Photos: (4)
Feedback Score: 0 reviews
and if the relief valve is indeed working as inteneded my statement above is incorrect according to the AC site you listed above. It appears that the relief valve DOES vent into the atmosphere. However, it also seems to be a last resort safety in a defective system. I would be interested to know what pressure that relief valve operates at.

I learned something today also!
__________________
2012 F350 Lariat ultimate 6.7 PSD LB CC SRW Fx4,
67 F-250 Project truck, currently in a billion pieces
70 F-250 4x4 (highboy)
Past trucks: 07 F-350 xlt 6.0 PSD LB CC SRW 4x4, black on tan, A/T, 5" exhaust w/4" downpipe, SCT livewire Traded in 04 F-250 xlt 6.0 PSD SB extcab 4x4, 6spd, all stock and 97 F-250HD xlt 7.3 PSD extcab LB 4x4, 5spd, Superchips tuner, 4" turbo back exaust, K&N CAI, 02 intercooler installed, Sold

Last edited by fireguywtc; 07-10-2012 at 02:12 PM.
fireguywtc is offline   Reply With Quote Quick reply to this message
Old 07-10-2012, 03:30 PM   #8 (permalink)
Senior Member
 
Join Date: Apr 1999
Location: Justin,Texas, Republic of TEXAS (USA)
Posts: 4,601
My Photos: (1)
Feedback Score: 0 reviews
The high side pressure needs to be checked. Usually these relief valves, when equipped, has opening around or a bit above 400psi. The fan clutch needs to be checked and check the air path through the cooling stack for bugs and debris.
The programming runs fan a bit when stopped and when road speed is low. If the high pressure switch on high side line closes fan operating duty cycle is increased for more fan speed. The fan operation should have a code if codes are read out if that is the problem. If the condenser is blocked then fan could work fine and still have a/c high press go too high and relief do a dump.
The engine would be running hotter than normal but you'd not know due to the "we're scare to tell the truth" gauge system Ford has used for a coupe of decades (not that you might be able to tell that I have an issue with gauges that are not much more good than a warning light...).
__________________
Don't tell my cattle I got leather seats!
2006 F450 CC Hauler bed 4x2 6.0 L Pstroke/Torqshift, Lariat, 4.30 r/a, SCT, 4in exhaust. 103K New heads to repair diesel in coolant.
2006 F350 Lariat CC Dually 4X2, 6.0 TorqShift 4.10 LS, SCT, airbags, 4 in. exhaust. 147K Rebuilt engine to repair damage from burned piston.
36 feet on the floor Elite/Outlaw LQ horse trailer.
36 foot double tandem axle flatbed trailer.
36 foot Sooner 6 horse large dressing/ mid tack.
2003 EB Expedition 149K (no engine repairs, gas burners are the new longevity leaders)
2004 Volvo V70R AWD-high miler in fleet, 215K (no engine repairs)
2007 BMW 550i 6MT 112K
jimmy is offline   Reply With Quote Quick reply to this message
Old 07-10-2012, 05:08 PM   #9 (permalink)
Senior Member
 
Join Date: Jan 2005
Location: South La
Posts: 147
My Photos: (0)
Feedback Score: 0 reviews
Good info, I just found out he had it in the shop for this today and they replaced the switches, and then the fan clutch. Thought they had it fixed, but it started doing it again. I'll advise him to check for air flow restrictions.

Thanks.
__________________
2014 F-350 Platinum SRW LB Ruby Red Metallic

2000 F-250 Lariat PSD 4X4 Auto CC SB 350,xxx miles, 4" Super-Lift/Fierce Attitude M/T LT31575R16's
Tymar intake, 4" turbo back MBRP exhaust, AIH delete, AC mod, ISSPRO gauges, PHP HYDRA, FFD Single Shot Stage 1's, FrX, Hutch/Harpoon Mods, Monsterbox Tranny, Tru-Cool Max

AE in Lafayette, La vicinity...
bmcnabb02 is offline   Reply With Quote Quick reply to this message
Old 07-10-2012, 06:30 PM   #10 (permalink)
Senior Member
 
ford_doctor's Avatar
 
Join Date: Jul 2004
Location: NJ Native
Posts: 3,093
My Photos: (1)
Feedback Score: 0 reviews
An A/C pressure relief valve is incorporated in the A/C compressor to prevent damage to the A/C compressor and other system components by relieving unusually high system discharge pressure buildups. On this particular system the valve opens at 550-600 psi.

Quote:
Originally Posted by bmcnabb02 View Post
My boss's truck, '09 F-250... he's having problems with some kind of relief valve relieving freon from the system. Changed the relief valve with no results... seems as if it's doing what it's supposed to do and relieving excess pressure. Any ideas why?
Obviously the refrigerant system is building too much pressure which is why it is venting. The system contains two pressure switches. A compressor clutch cycling switch and a high-pressure cutoff switch. This switch is used to interrupt A/C compressor operation in the event of excessively high discharge pressure in the high-pressure side of the refrigerant system. The PCM monitors the contacts in the high-pressure cutoff switch. When the high-pressure cutoff switch is open, the PCM will disengage the A/C compressor clutch.

You need to understand that the PCM is actually in control of supplying power to the clutch by controlling the clutch relay. The high pressure cut off switch is monitored by the PCM. With that said, you have an electrical concern. Checking the PCM for codes is actually a good place to start as your concern could be the high pressure switch, the wiring or a faulty clutch relay... least likely but still possible... the PCM.

There is also the chance that the compressor clutch is locked as well. With the engine off and the FEAD belt removed the compressor pulley should spin freely and smoothly.

Good Luck!
__________________
.
Ford Senior Master Diesel Technician
Diesel Technician Society
Diesel Mentor Directory

Last edited by ford_doctor; 07-10-2012 at 06:38 PM.
ford_doctor is offline   Reply With Quote Quick reply to this message
Old 07-11-2012, 09:12 AM   #11 (permalink)
Senior Member
 
Join Date: Jan 2005
Location: South La
Posts: 147
My Photos: (0)
Feedback Score: 0 reviews
Thank you!
__________________
2014 F-350 Platinum SRW LB Ruby Red Metallic

2000 F-250 Lariat PSD 4X4 Auto CC SB 350,xxx miles, 4" Super-Lift/Fierce Attitude M/T LT31575R16's
Tymar intake, 4" turbo back MBRP exhaust, AIH delete, AC mod, ISSPRO gauges, PHP HYDRA, FFD Single Shot Stage 1's, FrX, Hutch/Harpoon Mods, Monsterbox Tranny, Tru-Cool Max

AE in Lafayette, La vicinity...
bmcnabb02 is offline   Reply With Quote Quick reply to this message
Old 07-21-2012, 09:37 AM   #12 (permalink)
Senior Member
 
Join Date: Jan 2005
Location: South La
Posts: 147
My Photos: (0)
Feedback Score: 0 reviews
Update,

Still an ongoing issue, but the same shop that replaced the switches and changed the fan clutch has completely tore the system apart and found the in-line filter (wherever that is) full of aluminum shavings. So now they are replacing the compressor & the accumulator.

I guess if they change enough parts they'll eventually fix it. lol
__________________
2014 F-350 Platinum SRW LB Ruby Red Metallic

2000 F-250 Lariat PSD 4X4 Auto CC SB 350,xxx miles, 4" Super-Lift/Fierce Attitude M/T LT31575R16's
Tymar intake, 4" turbo back MBRP exhaust, AIH delete, AC mod, ISSPRO gauges, PHP HYDRA, FFD Single Shot Stage 1's, FrX, Hutch/Harpoon Mods, Monsterbox Tranny, Tru-Cool Max

AE in Lafayette, La vicinity...
bmcnabb02 is offline   Reply With Quote Quick reply to this message
Old 07-21-2012, 09:49 AM   #13 (permalink)
RT
Lifetime Supporting Member
Lifetime Supporting Member
 
RT's Avatar
 
Join Date: Dec 2009
Location: Texas
Posts: 9,968
My Photos: (0)
Feedback Score: 0 reviews
Quote:
Originally Posted by bmcnabb02 View Post

I guess if they change enough parts they'll eventually fix it. lol
One would hope so - unfortunately, if they don't change enough of them at once - you'll be back where you started. Aluminum shavings would almost have to be from the compressor. From there, refrigerant gets pushed into the condenser where the gas liquefies. From there through the "filter" which is built into the orifice tube - from there to the the accumulator / drier.

So - if they don't flush the condenser adequately - which is almost impossible to do - you'll get a fresh spray of aluminum shavings heading for the orifice tube the first time you turn the a/c on.
__________________
2003 F-250 XLT Crew Cab 7.3L, Chrome BigTex Grille Guard, Quad pillar - 3 ISSPRO gauges (trans, pyro, boost) and DP-Tuner F6; Roush fuel pressure / temperature / oil pressure gauges, Ford Severe Duty AIS, 31 row 6.0 transmission cooler, ScanGauge II, Marinco mod, Walker BTM
RT is offline   Reply With Quote Quick reply to this message
Old 07-21-2012, 12:59 PM   #14 (permalink)
Senior Member
 
fireguywtc's Avatar
 
Join Date: Jun 2008
Location: central tx
Posts: 539
My Photos: (4)
Feedback Score: 0 reviews
agreed. ask them to replace the condenser. Its in the neighborhood of $250 and is well worth the piece of mind in this scenario.
__________________
2012 F350 Lariat ultimate 6.7 PSD LB CC SRW Fx4,
67 F-250 Project truck, currently in a billion pieces
70 F-250 4x4 (highboy)
Past trucks: 07 F-350 xlt 6.0 PSD LB CC SRW 4x4, black on tan, A/T, 5" exhaust w/4" downpipe, SCT livewire Traded in 04 F-250 xlt 6.0 PSD SB extcab 4x4, 6spd, all stock and 97 F-250HD xlt 7.3 PSD extcab LB 4x4, 5spd, Superchips tuner, 4" turbo back exaust, K&N CAI, 02 intercooler installed, Sold
fireguywtc is offline   Reply With Quote Quick reply to this message
Old 07-21-2012, 01:24 PM   #15 (permalink)
Senior Member
 
ford_doctor's Avatar
 
Join Date: Jul 2004
Location: NJ Native
Posts: 3,093
My Photos: (1)
Feedback Score: 0 reviews
That is not a filter, it is the fixed orifice tube which has a screen on both ends. it is cleanable depending on the type of debris it collects. If the compressor has in fact failed then the advice to replace the condenser core is wise. The lines can be flushed. The receiver dryer, evaporator and low pressure line are for the most part protected by the screen on the orifice tube and can be reused.

I still think that you have an electrical concern because the high pressure cut off switch is supposed to prevent the system from reaching the pressure required to open the relief valve in the first place. That is why the switch is sometimes referred to as a "refrigerant Containment Switch.".
__________________
.
Ford Senior Master Diesel Technician
Diesel Technician Society
Diesel Mentor Directory

Last edited by ford_doctor; 07-21-2012 at 01:45 PM.
ford_doctor is offline   Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

  Diesel Forum - TheDieselStop.com > 2008-2010 Ford Super Duties > 6.4L Power Stroke Engine and Drivetrain

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Diesel Forum - TheDieselStop.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



Wheel & Tire Center

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 02:57 AM.



Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.