A/C Cuts Off Sporadically at Normal Highway Speeds

[RC-02-Sport-Trak]

My 2002 Sport Trac has been a real champ, until the last few months. I really can't complain as I have nearly 210,000 miles on it. Been a great vehicle, hope it continues. Uses no oil at all. Have owned since new.

In the last month the A/C has started cutting off sporadically at normal highway speeds. Usually comes back on after a few minutes. I am wondering if it might be the magnetic clutch cutting out. I put coolant in the system last year (2013) for 1st time.

Yesterday - 08/05 - I was running errands and got stuck in traffic for about at least 15 minutes. The A/C was on max, cooling fine. It was near 100 outside. I know the compressor will cut out on hard acceleration. The A/C cut out as I was merging onto the interstate. It wouldn't come back on. Usually switching from whatever A/C setting your on to the other setting (e.g., Max to "plain" A/C) causes the A/C to come back on. Not this time. I switched it to vent for about 2 or 3 minutes. Then, switched back to MAX A/C. It came back on.

I have never had an auto A/C unit do this. That is why I was wondering about the clutch. I have not checked the coolant level, as when the A/C works, it cools great.

Any ideas? This red face is not anger. It's HOT!

 

[Maniak]

Using a set of feeler gauges you can see if the air gap is too big on the a/c clutch. That was the problem on our mustang when the a/c would cut out randomly.

Also, if the system is low on r-134 it could shut off when running at the higher rpms since the pressure differential could bring the low down too far.

Of course, having a blockage in the system can also make things shut off. As your heading the freeway your trying to push more r-134 through the system and if things are overly restricted the pressures can get too high and assuming your rig has the high pressure cut-off switch, it will turn off the compressor.

~Mark

 

[Bobmbx]

You probably have a slow freon leak.

Something else to check is your orifice tube, which may be clogged. Although I'm not certain the 2002s have an orifice tube. They may have an expansion valve. Checking the tube will require the system to be opened, though.

 

[RC-02-Sport-Trak]

A/C Cutting off at Normal Freeway Speeds

Thanks folks. I appreciate the input.

I had thought it might be a slow leak, but thought I would solicit some input from you folks.

It might also be a blockage, considering the age of the system. I know... blockages can happen at any point in the "systems' " life. The same is true of a leak.

I will check the refrigerant first. If it's okay, then, I will dig further.

Again, I really cannot complain, as for the most part, this vehicle has been trouble-free, except for routine things.

Thanks folks for the input.

I forgot to add that this is an "on demand" 4x4 vehicle. Have loved it, since we head off to the "country" or the mountains regularly.
BC