All these Air Conditioning threads for summer 2011!

I couldn't find the answer to my question though.

I checked my AC system PSI and it was at 40 on a day that was 105 outside so according to what I read I could take it up to 55psi and it would be the optimum pressure. I put in one can of 12oz 134a non-sealer/non-dye/non-F'youp in a can and it took the pressure up to 45psi after running it for 30 or so minutes on MAX cool.

Next day I went and got another can of 12oz 134a pure, hooked up the line I was still at 45psi and it was 95 degrees which was the min temp for 55psi AC system, so I added the second can and I dropped my AC PSI to 40.

I ran the system for 30minutes while I drove around and the cooling temperature wasn't any less then what it was the previous day.

I started the whole AC system check out because the wife said it wasn't cooling as much as her '07 Tahoe and I said, it is a newer system to begin with plus it is probably more efficient and less leaks; it might never ever get as cool as your system but let me check further. I didn't think it was all that bad.

I got out my laser temp gun and it was 102 degrees outside, I checked the registers on my side of the truck and they read 50 to 54 degrees, I checked the passenger side where the wife sits(not sexist) and the temperatures were consistently 10 degrees hotter then the driver side. 62-67 degrees. My initial guess while not tearing into it while it is blazing hot outside is that her side has a leak in the hoses somewhere that is either leaking out cold air or letting in hot.

My question is, what is the average temp everybody else is getting out of their systems? 50-67 seem normal on a 102 degree 20% humidity day?

Also, any other thoughts on why there is a ten degree difference from the far side of the evaporator, to the closer hotter side of the evap system?

 

Do you have the shut-off valve to stop the coolant flow to the heater core? It sure made a difference on my truck, just a guess but with the pass side closer to the heater core might explain your temp diffs...just thinking out loud

 

Shut off valve (most Az trucks have them) and have you ever cleaned your evaporator core here in the valley it's so dirty the cores get plugged in just a few years! And this will give you all kinds of trouble especially come monsoon season, my two cents, good luck!

 

I've not done the coolant mod to the heater core, I guess I need to look into it. I read it but was hesitant to do such a thing as it appears, to me, to add some extra complication for not that huge of a pay off. But I might be seriously wrong, it seems, might be just what I need.

I did flush out the evaporator as my first digs into a fix. I took the rat cage out and put in a scope to look things over first and it did not appear to be blocked at all, dusty for sure but nothing like the pics I've seen of people taking theirs apart. Even once I started with the hose the water didn't come out black and stay dirty for awhile, it was a quick dust color to clear water, so I just made sure to put a lot through it.

On the condenser, I unbolted everything and got to where I could get a hose behind it and gave it a good washing as well. I then took a fin comb and spent an entire evening getting all the rock strikes out so air would flow through it proper. It might have had a 25-30% reduction in airflow after nine years of crap shooting at it down the road.

I might have to take it in for a professional to give it a once over, I still need to gap check the compressor, I have not done that, but mine seems to work normal and engage once the AC is turned on, don't think I've seen it turn off though once I turn the heat up and the AC is on Normal.

 

On my 03 I have a factory installed heater core bypass already, found that out when I was looking to do that mod. It's on the heater lines about 6 to 8 inches from the firewall, looks like a plastic disc with a little vaccum line going to it, check to see if you have one already, not sure what year they started that. As for the temps, IMO, they arn't bad temps inside the cab for what kind of heat your seeing. As for the different temps on either side, no clue, good luck though..

 

Your pressure is wayyy to high! It needs to run around 30psi on the low side.
More pressure is not better.

 

It should be in the low 40s for low-side pressure at 100-105 F. I just redid mine Sunday (new compressor and receiver-dryer), and with the 42 oz of R134 weighed into the system after being evacuated for an hour, my low-side war around 40-45psi. My high-side was 250-275 psi. Also, it's normal for the low-side pressure to go up then drop on 134A systems. Check your compressor and the suction line from coming from the evap core. Mine is cold all the way to the compressor now where it wasn't before.

 

On a hot 90 degree day. Mine will blow 45 degrees. if i turn off the heater hose manually it will dip into the mid to upper 30's.. Burr.. Low 40's for pressure.

 

Well if you were getting a 50 degree difference between ambient and interior, your way ahead to start with. These systems were designed with the capacity for about 30 degrees of differentiation. Removing the heater core from the equation which sports about 190 degrees with untold amount of BTU capacity, certainly will help!

What was your high side reading?

 

You should do the heater core mod. It makes a nice difference, and every bit helps. My temps are around 52 degrees.

 

I don't have the high side gauge to connect and see, need to ask a couple mechanic buddies if they have them.

I need to check and see if mine already has one like Bigpappa said and if not I'll do after this weeks 115 degree heat.

 

BB, check out this link https://www.ford-trucks.com/forums/1...am-ac-mod.html , click post #7 on Robin's AC mod and the first pic is what you'll be looking for. If the heater core control valve isn't there, this thread with everybody's info will guide you..

 

This was my results after the mod. Avg ambient temp 85-90 truck running/driving for 15 minutes and this is the temp on Max AC lowest fan speed setting.

 

Now we know the cause of global cooling .

 

Thanks again Big Poppa, that's exactly what I was looking for info wise. I need to check my local autostores or stealerships to find a good price on it now.


When I first checked this thread I did it on my cell phone and seeing your pic I thought, 77 degrees? What a waste of time! But now on my computer I see it is 7.....huge difference.