A/C problems, and it's the HOTTEST day on record here!

[Todd W. White]

Hi folks!

I've corresponded some with BrooklynBay about this, and he suggested I post, even though I'm a newcomer here.

Stats:

1994 Aerostar with 3.0 L V-6, Auto, front and rear A/C. 293,000 miles, with 55,000 on the engine rebuild, 14,000 on the transmission rebuild. New alternator within the past year, and a new water pump, which I installed last week.

Problem:

Just bought this, but I had a 1992 before and liked it, so I got this one when it came up for sale on C/L for $800. It went so low because the A/C was out.

I had my friendly auto A/C guy replace the blown out high-pressure line (actually, we had a local company rebuild it), replaced the compressor, which was locked up, flushed the system and recharged. Also cleaned the front inside coils and the main coil out front.

It didn't cool properly, though it was properly charged.

We found some vacuum leaks, which BrooklynBay helped me locate, and that seemed to fix the problem of the air diverting to the defroster vent in the front and the floor in the rear, but it's not cooling adequately. At best, I'm getting 60-62 degrees coming out the front vent with an ambient outside of 95-degrees.

It seems I still have a vacuum problem.

Here's what makes me think that:

While driving at about 25 mph, but not pushing the engine, I can switch from NORMAL to MAX AIR and hear the damper close (at least partially), and the air speed increases and the amount of cold coming out of the vent increases noticeably, even though it's 113-degrees outside right now.

However -

When I begin to accelerate, the air flow drops off a bit, but not as slow as when it's set on NORMAL, and the air gets warmer.

Questions:

1. Is this a possible vacuum leak?

2. If so, could this be a faulty "check valve", or am I searching for another leak?

3. If not, what do you feel it is?

THANKS in advance for your advice, as I do NOT want to go out and hunt in vain in this heat!

- Todd in Sapulpa, OKlahoma, where we're scheduled to set all previous hottest-days-on-record today!

 

[BrooklynBay]

Welcome to this forum! Was a vacuum pump used on the A/C system prior to filling it with freon? Was the orifice tube replaced? Did you use a jumper wire to prevent the compressor from cycling while filling the system with freon?

 

[ragajungle]

Another angle: When I drive at 30-35 mph at a steady speed the a/c in my car cranks out frigid air. When I go to step on it the a/c disengages slightly (warmer air out the vents) until I reach and maintain a steady speed. Could the clutch be too sensitive? perhaps disengaging under mild acceleration?

 

[BrooklynBay]

You could test the pressure at different RPM speeds. Sometimes the A/C low pressure cut out switch could be defective or out of specification.

 

[Todd W. White]

OK, after MUCH consternation, here's what we found -

1. Yes, the man is a professional and did service the system properly.

2. I did a lot a tracing down of vacuum leaks -

* I found that the hot water control valves on the front and rear systems are NOT putting hot water into the heater core when the A/C is running - they only do so when they're supposed to.

* I found that the little check valve that is in the supply line for the vacuum-operated dampers and shutters was failing - it only worked part of the time. I called Ford and there is only ONE factory original in the entire State of Oklahoma, where I live! Included with it are the hoses, and they wanted a whopping $65 for it!

So - I said "the heck with that!", and found one that works perfectly at AutoZone. It was in their area where they have the "HELP!" items from Dorman Products. It is item #47149 "Vacuum Check Valve". I put a tiewrap on the small line and a worm-gear hose clamp on the larger hose side, so as to prevent leaks.

* The line going to the damper that changes the air direction to go to the defroster had a leak in it. I replaced it.

* The line going from the check valve to the "T" by the blower motor was also losing air.

These fixes solved the diverting problem.

Now - about the cooling problem, proper:

When I bought this Aerostar, the owner told me the A/C didn't work, and that his A/C man told him the high pressure line had blown.

Indeed, it had, and my man had a new one made, flushed and evacuated the front system, and charged it.

What we didn't know is that the compressor was locked up, as well.

So-------

A compressor had to be ordered, the system evacuated, the compressor installed, etc., etc., and then recharged.

It cooled, but not well - and now we know why.

When the FRONT system is on by itself, it works GREAT! After about 20 minutes of highway driving, it gets down to around 41-degrees coming out the front vents, and that's with an outside temperature of 114!

BUT - when the REAR system is also turned on, neither front nor back get colder than 62-65 degrees.

My A/C man and I have decided it must be the expansion valve in the rear system - it must have failed when the compressor died. He said compressors dump a lot of junk in the system when they give up the ghost.

So------------

I'm not running the rear system until I can save up for the expansion valve. Then, he'll evacuate the rear system, flush it, replace the expansion valve, etc., then recharge it.

I hope this fixes the problem.

 

[speleopower]

I just went through an A/C rebuild in my 97 Aerostar with front AC only. I found the only way to really fix the problem is to take the whole A/C system out and rebuild it with new parts and have the hoses rebuilt.
I found the condenser, evaporator and compressor all had small leaks. Yes the compressor will put a lot of crap into the system when it goes hence the reason to replace all of the components and start over with a new A/C. I got to the point I could remove the entire A/C system and replace it in under 4 hours. That is after I took my system out several times to track down problems.

-Scott