Oooo K, So… AC question…

[TheGuyWho]

I did some work on my Expedition that I only bought a few weeks ago. When I bought it the AC wasn't working (among other things), as in the front vents did not blow air at all. I figured it just needed a recharge. SO I did that. Put two cans in it too. After the fact I found a vacuum hose had been severed, so I fixed that, and walla! AC again… However, it is not blowing as cold as I would prefer. Is there anything I can do to make it colder?
Part 2:
While I drove it today I noticed something else that was weird to me. While driving up hill and under stress the ac would shut off. Under hard acceleration it would do it sometimes, but sometimes not. Once I lifted off the gas the AC would come back on. Now I know that when I had my mustangs the ac would shut off under hard acceleration, but it was never THIS noticeable, Annnd it was different because the vents would still blow. With my issue it stops blowing air out of the vents all together.
Does anyone know why?

 

[walnuts4x4]

have you made sure your blend door is working?

 

[Racenut]

The reason the A/C will stop blowing completly is because all of the blend and position doors are vaccum operated.

When the motor is under a heavy load or you are at WOT vaccum levels diminish and the doors will actually close until they have enough vaccum to reopen.

As for the A/C not being cold enough I have noticed that with these (Expeditions) being so large it takes a good amount of time for it to get really cold ( after 30min interstate driving with outside temp of 100+ I some times have to shut mine off for a bit cause it is so cold) and if you are doing nothing but intown driving good luck it will not get very cold.

About the best thing would be to get rid of the factory clutch fan and go electric or add on a front mounted "PUSHER" electric fan to suplement the factory fan. With only the factory clutch fan intown you do not have enough air flow over the A/C condensor to get the system working at it's optimum level (The more air the better) thats why they do alot better when you are interstate driving.

 

[Fastcat]

I don't think its 100 degrees anywhere in the states as of now lol. But after u put the 2 cans in did u check the line pressure? If its too high or too low the ac won't blow cold. I think its suppose to be inbetween 30 to 35psi

 

[TheGuyWho]

have you made sure your blend door is working?

No, I have not. How do I check that?

 

[TheGuyWho]

The reason the A/C will stop blowing completly is because all of the blend and position doors are vaccum operated.

When the motor is under a heavy load or you are at WOT vaccum levels diminish and the doors will actually close until they have enough vaccum to reopen.

As for the A/C not being cold enough I have noticed that with these (Expeditions) being so large it takes a good amount of time for it to get really cold ( after 30min interstate driving with outside temp of 100+ I some times have to shut mine off for a bit cause it is so cold) and if you are doing nothing but intown driving good luck it will not get very cold.

About the best thing would be to get rid of the factory clutch fan and go electric or add on a front mounted "PUSHER" electric fan to suplement the factory fan. With only the factory clutch fan intown you do not have enough air flow over the A/C condensor to get the system working at it's optimum level (The more air the better) thats why they do alot better when you are interstate driving.

Im definitely planning to drop an E-fan in her. Just gotta find the right one.

 

[buildingdoc]

Its not that simple guys...

You would be correct as far as the vacuum line goes as the selector switches are vacuum operated. But as far as the refrigerant system it could be a few things...

1. If you had to add refrigerant (R134a) then the original refrigerant possibly excaped to atmosphere due to a leak! This is not a fuel system and it does not get consumed. It is a cycle. I would find the leak and have it repaired.

2. The reason your A/C kicked off is because you either over charged the system (2 cans is not a precise way to measure refrigerant and these systems are small and require a specific amount. Look for the decal under to hood that tells you how much for a front or front and rear system as it applies.) or it is leaking still and undercharged. While charging the system you may have had a little gauge that would be in the green zone. That is usually to measure the low side pressure and it would be between 30-40 psi. That is good. But there is a low pressure cut off switch that will cut off the compressor under 32 psi and that may be the case under acceleration since the compressor suction will drop the faster the compressor turns. Same for the high side. But this increases the high side pressure and the switch for the high side usually cuts the compressor out over 300 psi. The low pressure switch may be adjustable, but I advise against it. You could starve the compressor without a safety of the switch as the refrigerant leaving the evaporator cools the compressor and thats a couple hundred bucks if it doesnt explode and just kills the valves.

3. R134a is a decent refrigerant.... but unless you are on MAX AC and vent all of the warm air out of the cab.... I wouldnt expect temps more than 30 degrees below the air you are trying to cool. R12 was much better at absorbing heat. An electric fan would be ideal, but not sure if it will do much. It would have to push more cubic feet of air (CFM) thann your stock fan to make a difference. I would check the fan clutch first. Start your engine.... turn it off and it the fan keeps spinning, replace the fan clutch. Should stop after a few revolutions.

4. Lastly, I would take it to a shop to have it evacuated, put under a vacuum( yes the refrigerant system) and properly recharged to the correct weight. The vacuum is a good way to tell if there is a leak in the system as it will not acheive 29.5"/hg. Another good reason is that moisture under a vacuum will boil off and be removed from the system. Moisture and refrigerant mixed creates an acid and will eat the entire system inside out.

I have had over 10 years of automotive AC and heating experience in case anyone was wondering.

Hope this helps and doesn't scare you too much.

Matt