AC not very cold- dealer response?

[Gifford]

I believe that my AC is not getting as cold as it should- yes I know its been unusually hot here, but I noticed this before the recent heat wave. THe temp is definitely not as cold as my 2nd gen was, that truck would freeze my knees after an hour on full blast, my new truck takes an hour to get to what I consider cold. Anyway, will the dealer charge me $90. 00 and tell me its normal or are there some objective measurments I can have them take?

 

[JCleary]

I have a similar problem, more noticeable on the right side. Also my system will freeze up after a while.



The dealer told me it was normal and there's nothing they could do under warranty. I could pay for a $149 A/C service, though, and it may fix the problem

 

[daytripper63]

Hey guys, I just went to Kragen and bought a charging kit with guage, r134 bottle and a hose and charged mine for about 60. 00 dollars and mine would freeze sometimes and was only cold on the drivers side the passenger side was so so

 

[JStieger]

Hey guys, I just went to Kragen and bought a charging kit with guage, r134 bottle and a hose and charged mine for about 60. 00 dollars and mine would freeze sometimes and was only cold on the drivers side the passenger side was so so

Did the recharge solve the problem? How does A/C recharging work anyway? Is there a set pressure setpoint or can one charge to another pressure to get better/worse performance?

 

[MMeier]

Definite do not want to overcharge. Keep in mind though when it is hot outside the pressure will be more also. If you buy a kit with a hose, buy one thats reusable, so you have it next time. Those kits that come with the hose/gauge, can all as one are a rip in my book. Gauge is usually color coded, so you know where you're at. Sometimes in hot weather, like here lately and when I had to add a can to my truck I ran a hose over the condenser(thingie in front of Intercooler up front) to help lower the pressure a bit. Good to go now and does not freeze up anymore, even with the high humidity here lately.

 

[jelag]

I have both a point and shoot temp gauge as well as one that sits in the air stream in one of the ducts... .



When its under 100 degrees outside... the temp gauge in the duct always hovers around 38-42 degrees..... no matter what blower speed the dash is set too... . this is with the temp knob on its lowest setting... ...



Above 100* outside. . and this rises to 40-44 * at the duct... ... I only assume it does this because the system is overwelmed with the outside temp and its not designed to be efficient enough to shead the heat from the freon when its that hot... .



We had a problem with our 04 at 200K miles with it now not coming back to temperature... . stayed about 10 * warmer than it should... I sent it to a local guy I trust and gave him a brief rundown of what was happening based on TEMPERATURES at the duct... . He had no problem fixing it and returning to normal... (the way it was for 190K miles. . ) I haven't seen a copy of the workorder so I don't have a clue what he did...



I just got off a 3500 mile trip where it was over 110* for 5 days... . and the temp stayed at the 40-44* mark... when the sun is beating into the cab through the windshield it doesn't keep up. . any other time its fine... ...



Hope this helps. .

 

[DPKetchum]

Very long thread on the http:/www.thedieseltruckresource.com/underMegacabac. DARN can't get the URL to work.

 

[Eric_77]

I have seen a few posts about this and will post what I have learned from a AC sage from Phoenix. I am not an AC tech just had to deal with major headache system. this refers to R134A



1. determine what service AC has had in the past recharge, oil, open to environment.



2. If system has unknown history then you need to start from square one.



[bold]A. Service if system has always been sealed and never serviced. [/Bold]

1. Pressures need to be checked on both high side and low side high, ambient temperture needs to be known.



2. Use gauge to be sure high side is ambient plus 45degrees F. (this is listed on many of the commercial gauge sets otherwise use this calculator )



3. low side should be ambient -70 degrees



4. now raise engine speed to operating speed and check pressures again



5. If pressures are off more than 30 PSI than system needs to be "reset" go to B



6. fill system to the proper pressures with R134a that does not contain oil or other additives (this is cause of issues as the system does not normally leak oil out and adding more causes more problems)



8. outlet temp should be ambient -55 or cooler otherwise need to check for other issues blocked evaporator, overloaded on oil, etc



[bold]B for system that have been opened/unknown[/bold]



1. disconnect all hoses and use air to blow oil, water from the system. Watch for rust, rust is bad compressor or other component and system will have to be flushed and components replaced.



2. Replace all orings and tighten fittings to spec.



3. pull vacumum for 30 minutes for every 10 % of relative humidty

(this boils the water out of the system which is major problem for cooling)



2. turn pump off for at least 30 minutes prior to filling and verify that vacumum is maintained.



3. fill system with a can of refrigerant.



4. Start engine and fill to pressures as Step A6 except use R134A with oil.

 

[robertyoke]

if your evaporator is in infact freezing (ice forming on the evaporator) then the fin sensor has fallen off the evap. or it is bad. if you overcharge the system the temp will actually rise. it's the pressure diffrential (low side to high side) that makes the system work. if you are low on refrigerant/or overcharged then the temp will never be cold enough to freeze.

the fin sensor will keep the temp. constant at the evaporator when the a/c is on reguardless of the temp setting or fan speed. the fin sensor tells the ecm to cycle the compressor on and off.

also if you overcharge the system, you may when the compressor is on,trip the high side limit switch and that will shut the comp. off, will trip the mil and set a code. or just go pop and all you refrigerant will be lost!! :-laf

-robert

 

[Jaysyl]

Definite do not want to overcharge. Keep in mind though when it is hot outside the pressure will be more also. If you buy a kit with a hose, buy one thats reusable, so you have it next time. Those kits that come with the hose/gauge, can all as one are a rip in my book. Gauge is usually color coded, so you know where you're at. Sometimes in hot weather, like here lately and when I had to add a can to my truck I ran a hose over the condenser(thingie in front of Intercooler up front) to help lower the pressure a bit. Good to go now and does not freeze up anymore, even with the high humidity here lately.

Humidity only 14% today. It sure felt a lot higher :{ :{

 

[PAllyn]

Auto Zone has a loan a tool program. You can get the professional A/C gauges. In the Service Manual it tells you what pressure levels should give what temps.

 

[Bob4x4]

A/C PERFORMANCE TEMPERATURE AND PRESSURE Ambient Air Temperature 21° C (70° F) 27° C (80° F) 32° C (90° F) 38° C (100° F) 43° C (110° F)

Air Temperature at Center Panel Outlet 7° C (45° F) 7° C (45° F) 13° C (55° F) 13° C (55° F) 18° C (64° F)

Compressor Inlet Pressure at Service Port (low Side) 138 to 207 kPa (20 to 30 psi) 172 to 241 kPa (25 to 35 psi) 207 to 276 kPa (30 to 40 psi) 241 to 310 kPa (35 to 45 psi) 276 to 345 kPa (40 to 50 psi)

Compressor Discharge Pressure at Service Port (High Side) 1034 to 1724 kPa (150 to 250 psi) 1379 to 2068 kPa (200 to 300 psi) 1724 to 2413 kPa (250 to 350 psi) 1999 to 2689 kPa (290 to 390 psi) 2413 to 2965 kPa (350 to 430 psi)





These are the pressures at temps that should be seen,as you can see 55* is all that is required @ 100 ambiant with the window open and engine @ 1000 rpm per fsm (03)



Bob

 

[AMink]

There's another thread going on about questionable a/c in the newer 3rd gens. I had the dealer check mine and, of course, it was working within spec. I know the Megacab is a large space to cool, but my wife's Expedition can do it, my extended cab Chevy at work does it, and my 97 CTD does it. Even with the fan on high, it just doesn't seem like there is a lot of volume coming out the vents, and what is there isn't particularly cold. I think the a/c unit in the newer trucks is just not up to the task, especially when it is above 95*. If you start with the a/c on when the truck is cool in the morning, it will keep up fine, but if you get in when the truck has been sitting in the sun and it's 130* in the cab, it doesn't catch up. It sucks that on a vehicle that costs as much as these trucks do, things like a/c are a weak spot. If someone comes up with a fix/repair/upgrade, please post it! I'm sweating so much I'm dehydrating!

 

[JStieger]

Well after I posted on this thread I jinxed my truck. I went to go run an errand and all that was coming from the A/C was warm, humid air - like a steamed up bathroom after a shower! I get the errand done after the truck sits for an hour and then after starting it, the A/C starts working for about 20 seconds and then CLUNK, then the truck dies. I check for codes and get P0647 "AC clutch relay circuit high voltage". I restart the truck and now the A/C works like it is at the North Pole! It was about 100 degrees out and the truck A/C worked fine the rest of the day.



It's almost as if something seized on the compressor enough to stop the truck from running.



Where is the evaporator and fin sensor? Also, what is the black canister just off the passenger side firewall?



Lastly, if it is the compressor, is it easy to change with no special tools?



I'll check the obvious A/C clutch relay first though...

 

[Idaho Native]

Is anyone else losing their A/C when accelerating from a stop? Mine seems to "quit" for about 30 seconds after leaving a red light or stop sign. Maybe I'm losing my mind but I though I had read something about it before...



Loren

 

[robertyoke]

Well after I posted on this thread I jinxed my truck. I went to go run an errand and all that was coming from the A/C was warm, humid air - like a steamed up bathroom after a shower! I get the errand done after the truck sits for an hour and then after starting it, the A/C starts working for about 20 seconds and then CLUNK, then the truck dies. I check for codes and get P0647 "AC clutch relay circuit high voltage". I restart the truck and now the A/C works like it is at the North Pole! It was about 100 degrees out and the truck A/C worked fine the rest of the day.



It's almost as if something seized on the compressor enough to stop the truck from running.



Where is the evaporator and fin sensor? Also, what is the black canister just off the passenger side firewall?



Lastly, if it is the compressor, is it easy to change with no special tools?



I'll check the obvious A/C clutch relay first though...

that does sound like the compressor is locking up.



evap and the sensor is in the dash, and a lot of work to get to.



the black canister is your accumulator/drier.



and you can not service your a/c without a vacuum pump. they are about 150~250 bucks. you will also need the quick disconnect tools for your lines $50 . the accumulator/drier will also need to be replaced if you open the system.

-robert

 

[Whiskey]

that does sound like the compressor is locking up.

evap and the sensor is in the dash, and a lot of work to get to.

the black canister is your accumulator/drier.

and you can not service your a/c without a vacuum pump. they are about 150~250 bucks. you will also need the quick disconnect tools for your lines $50 . the accumulator/drier will also need to be replaced if you open the system.
-robert

I just wonder if anyone has checked their serpentine. belt?#ad



I checked mine it was crappy on the inside of it , most likely to cause slipping on high demand. I'm not a expert but these nw trucks are controled by computers, so if the voltage is low on priorty things, maybe the computer takes it away from the blower fan.
If I am wrong, please comment. #ad

 

[JStieger]

I just wonder if anyone has checked their serpentine. belt?#ad






I checked mine it was crappy on the inside of it , most likely to cause slipping on high demand. I'm not a expert but these nw trucks are controled by computers, so if the voltage is low on priorty things, maybe the computer takes it away from the blower fan.

If I am wrong, please comment. #ad

My belt is good; I've had it off and on a few times in the last month when changing CP3's. When it is really cold out, my blower sometimes will not work until the grid heaters stop cycling. It's been this way ever since new in February 2003!



Robert - Sounds like a good excuse to buy some more tools! All kidding aside, do you recommend A/C work for an A/C system novice like myself or is it best left to a pro? I do not like the local dealer here because they are pretty useless and can even screw up adding windshield washer fluid to a vehicle! :{ :-laf

 

[robertyoke]

on my 98 truck, with 22k on the clock, the a/c never worked well from day one. the dealer put freon in it and said the temps were in spec 55 deg at the vent(on a 75 deg day). the pressures were near equal but if the book says temps are ok then disreguard the pressure reading. I knew better and bought a re-man compressor and new drier and changed the fittings from a r-12 vacuum machine that I got for free and I never had any more problems.

I dont like the dealers, I think most are crooks! I am not a mechanic but my father owned a service garage in ohio and I grew up around cars. there is nothing that I will not try to fix on one of my trucks,cars,motorcycles,atv,or snowmobiles. If you can read you can fix it!

go for it.

I to like to buy tools. I look at it this way you may spend $ on tools but you will have that tool for more than one job, or you can pay the same for someone to fix it for you and have no tools. (then buy the tool later so you can fix it right ).

-robert

 

[JVantreese]

I had a simular problem and the dealer evacuated the system to make sure that moisture was not causing the problem. They said that my factory fill was also higher then the specs called for. An over fill can decrease performance. I feel that it is better then it was but it seems that the system is barely adequate when the temp is above 90. When the temp is over 95 I find that I have to use the recirculate setting to keep my cool.