AC Issue

[red423]

Ok I know thi shas been asked 10k times my AC just doesn't seem to be right. I just changed the fan clutch, and still have 45 psi on the low side at ilde I have a 97 degree ambient with a temp of 71 at the center air outlets, when I rev the truck up to say 1800 rpm the low side pressure will go down to below 30 lbs and slowly come back. What the heck am I missing??? Driving down the highway it will cool but not freeze your ass out. I see guys on here getting 50 55 degrees discharge temps, wifes Pilot, is blowing cold as the day we got it, I just sold a 96 bronco that would make ice, I live in Miami, and going to a garage is a limited option, I have no idea who to trust down here. I could really use
some advice. I thought it may be a bad cabin filter, or a blocked evap, (air flow) how does one get to it to check????

 

[stamp11127]

First thing to check is the blend door. Make sure it isn't leaking some hot air into the system. Next would be the static pressure and ambient temp when checking along with the high side pressure when running. The low side is getting close to the lower limit if it is dropping under 30. This will cut out the compressor until the pressure builds back up.
Without knowing the static and high side pressure I would venture your problem is low refrigerant or a partially blocked accumulator.

 

[red423]

wish i was up near you............

I was flipping the can of 134 around and noticed a charging chart, saw where they recommend 45-55 low side at 95 ambient. Now I got a 25degree spread but still warming at idle. any ideas gauges are now busted will have to get a set tomm. boy I wish I had that bronco ac system back.

 

[stamp11127]

Yes the weather was nice up here last week. Has been raining all day and forecasted to rain most of next week. Going back to hot and humid.

We need to know the high side pressure before anything else. Get a good set of gauges that are liquid filled. I started with a cheaper set from HF - ended up being a waste of money. I now have a set of spare hoses should I ever need them.

Have you added any 134 to the system?

 

[red423]

Yes added gas

ok I got a set of gauges, at a 94 ambient, I have 248/54, at an idle speed of 650 rpm, this is in the sun with the sun blasting on the condensor, we checked with a digital temp, and the direct sunlight on the ground is around 104. I also noticed with the a/c on or off there is no change in engine idle, I looked it up and it says 550rpm is idle speed but it doesn't say what that idle should be with a/c running.
Question here is this, truck cools great on the highway, will go to 69 cycle on auto, buut when idling the temp sucks (goes warm) I know it should be related to the fan and air flow across condenser, when I increase idle to say 900-1000 it will cool better but not great, ok what am I missing? Could it be an air flow restriction across evaporator? Truck is 03, I am guessing there is a way to clean that evap without pulling the dash? or is my problem condenser related and I should start thinking electric fan? I really wanted to get my front seats recovered next but this cooling problem which seems to be getting worse and worse at idle needs to be addressed. thanks red423

 

[Copper93]

Spray out the condenser real good. Bugs, dust and debris will reduce the air flow. Is the fan shroud intact? The shroud forces the fan to pull through the radiator and condenser. Even one piece missing will reduce the air draw.

 

[stamp11127]

Check this site for pressure / temp readings.
R134a Refrigerant Pressure Temperature Calculator

With the system being at idle for a few hours, take a reading of the static pressure - do not run the system. This will tell you the ballpark amount of refrigerant that is in the system. At 94 you should have slightly under 115lbs.

I prefer to run the low side in the mid 40's for pressure. Yours is high to me, your low side pressure will equal around 57 degrees - check with the thermometer on the lines going into and out of the accumulator, plus the accumulator temp.

Has any 134 been added to the system? Make sure the fan clutch is working, if it isn't the pressures will rise and cooling drops off.

 

[GAINMOB]

thermostat?

 

[red423]

I just saw these messages today, I have a few minutes this a.m. and will blow out the condenser with a water hose, pressures stay intact, if I go to less than 54 low with this heat we been having I loose cooling except at highway speed. I will clean that condenser and get back to ya'll, the shroud is intact,, seems to be cooling a bit better since I added gas, it will cycle on auto if i run down the road a couple miles and it runs really well in the evenings and at night, it's that blasting Florida sun during the day and red lights which seem to handicap it. Thanks for the help, I 'm a going to try the above and get back to ya'll red423..............................

 

[Hamfisted]

Red is the air colder from the rear AC outlets than from the front vents ? Just wondering because the rear has a separate evaporator and blend doors, this can usually help you diagnose some issues. If the temps are the same front and back then you have to look at the common component(s), such as system charge, compressor, condenser... . Here's a nice write up on general system diagnosis : AC system charge and diagnosis. You should check system pressures with RPMs stable at 1000. Are you the original owner of the truck ?


-Mike

 

[red423]

Thanks just saw this today

No I am not the original owner, but I stayed in a Holiday Inn Express last night. I have the same cooling temps front and back, I tried to clean out the condenser and it is still grungy on the lower 1/4 I have coil clean and will try to use some when I get the time. It does work really well in the evenings and driving say from North Dade to Sunrise. Thing I can't figure out is I had a 96 bronco and it would make Ice, this expy is an 03 and struggles at red lights, also you say the engine rpm should be 1000, ok how is that??? I have looked all over for RPM with a/c on and can't find a chart, it's a 5.4 should I adjust it to 1,000 with the stop screw?? I would have thought there would be a computer controlled idle if the a/c is turned on to compensate for the engine drag by the compressor, or am I wrong?? My idle sits at around 800 and I know that extra 200 rpm would probably boost it enough to compensate the a/c when stopped but i cannot find anything related to idle. I believe even Hayes says it's 650 at idle. any info is greatly appreciated thanks red423

 

[Jb14]

I had a long term A/C issue that I was finally able to get repaired. Two issues one was a bad clutch fan the second was the main A/C hose that connects with the compressor their was a small crack in the connector that goes directly to the compressor. This will let in warm air and eventually drain freon. I took to 3 machaics before it was diognosed correctly. The part is about $260 from ford IF this is your issue. NOTE: Due to where this part leaks mechanics commonly mistake for a bad compressor as they think the compressor is leaking from the back. Good luck

 

[red423]

Thanks for responding you guys

I have been rather busy haven't had a lot of time to look into the AC issue, we went on a trip and she ran fine, except at red lights. I have some time today I will coilo clean the condenser and if need be I am going to adjust the idle up to say 950 with the stop screw and leave it.
If I run the idle to 1000 that ac works pretty good but with the idle at 800 it won't. I keep you posted red423

 

[buildingdoc]

Hey red.... did you recently change the compressor or has it been changed before? Could haveva bad condenser. .. partially clogged. Or your txv could be going out as well

 

[red423]

No I haven't

I just got this reply today,thanks, that a/c is the wierdest running one I have seen. Yesterday we took out the boat, it ran ok getting gas, then ran so-so at the dock, then blasted it cold when we were bringing in the boat.
Most of the time the trucks idle is around 650, even with a/c on, I can't find a definitive, idle speed in drive with the ac on, but I will try to up it a little bit.
Today I will check the blend door, I don't hear that rush of air when you hit the recirc air switch, so it may be a broken door foot, I will try to spend some time this morning and see if I pull the glove box if I can see that door.
Have any of you guys ordered used front seats off ebay and had any luck with them??? I was quoted 550 a seat to recover, and don't know who to trust down here in banana land to even work on my truck. red423

 

[Miami]

I believe the last trust worthy mechanic has left Miami, but if you happen to find one, PLEASE let me know...

 

[stamp11127]

Jacking up the idle speed is a bandaid to the problem for now but doesn't solve your problem.

Since the low side pressure is dropping when you increase the engine rpm, that indicates low refrigerant or blockage in the evap or drier.

Is anything icing up?

Has the system been opened? Has anything been added (r134a)?

There are times where it is faster to evacuate and recharge the system so that it is back to the factory standard before troubleshooting. That removes anything previous attempts have tried to fix.

 

[red423]

no system hasn't been opened as far as i can tell, buuuuttt, the ambient temp has dropped around 10 degrees here in banana land and guess what? That AC works pretty good. But that still doesn't explain when we have ambient temp of 94 it slows cooling at red lights.
I really want to understand and know why my idle with ac running is only 650?? Is this or not the proper idle speed when ac is on???????????
Also where is a proper charging chart for 134a??? I looked here and the one here is way off the one shown by a ford dealer on Youtube, maybe one of you guys can tell me at say 92 degree ambient, what should high and low side pressure be EXACTLY???????
On the cans you get from Advance they have a chart, most say 45-55lbs. buuuutt I also watched a YT video where a guy charged a expy, and he set ls pressure 60-65 lbs. so which is it?? oh and if I could afford a charging scale and a 20 lb bottle of 134a I would do it that way, so please, don't comment the proper gas amt is set on label in engine compartment. thanks red423

 

[Copper93]

The pressure is dependent on the ambient tempurature. The hotter it is the higher the pressure. 134a doesn't cool as well as the old r12. It is very reliant on air flow to cool. All the A/Cs with 134a will show a tempurature rise at a stop unless it has electric fans.

 

[stamp11127]

I go by this chart:
http://www.mastercool.com/media/89660-INST_web.pdf

You can tell by this chart that 65lbs on the low side is way off. I usually weigh the 134 after an evac or go by pressures when they just want the cheap fix.

I prefer to stay on the lower figures of the ranges given - just out of habit.

I don't remember my idle speed changing when I turn the a/c on, so that would be about right. I'll look later and see what it is.

If you can't get this fixed you may need to pull a vacuum and refill. If you have access to a decent compressor those wedge shaped "pumps" really do work. I was surprised to see one pull 29".