AC loses power after driving for a while?

[radio_guy]

Hi Everyone!

I have a '93 4D explorer - only has 75K miles.

The AC works great when the car is started, but if we're on a drive longer than say, 30 or 45 minutes, it loses power. Meaning that even on full blast, the air really barely pushes out anything at all. It's still cold, there's just not good air flow.

I've googled it to no end, and can find nothing that replicates this issue. You guys know what it might be?

Thanks!!

 

[arco777]

If the airflow itself and not the temp is the issue, might look at your fan blower motor - might be getting weak or getting hot.

 

[Jason94sport]

It's freezing up. I had it happen. On the X & other older mid 90's cars with sucky AC. Either the pressure switch is bad or the charge is not right.

 

[radio_guy]

Thanks for the responses guys.

Are any of these things big time $$$? Doesn't sound like they are...

 

[arco777]

Blower motor is pretty cheap if you get a junkyard unit, or new for about $33 from RockAuto.

Adding some freon is pretty cheap, you can get a DIY kit for around $20 at WalMart or any auto parts store. Pressure switch is probably pretty cheap too.

So can you describe your problem again in more detail? Are you getting reduced airflow out of the vents as time goes on, or is the air coming out getting less and less cold? When the engine is cold started and AC is switched on, does the compressor stay engaged constantly or does it cycle on and off? When air begins to not blow cold, is the compressor cycling on/off or is it staying engaged?

 

[R&T Babich]

...Adding some freon is pretty cheap, you can get a DIY kit for around $20 at WalMart or any auto parts store. ...

Unless radio_guy has converted the system to R134 adding some R12 freon could be tough. Ford didn't convert to R134 until 1994 in the Explorers and Walmart only carries R134. Interesting that Ford added the heater bypass valve at the same time they converted to the not as efficient R134. I'm adding the valve to our '92 & '93. A similar valve was used on the 1969 Ford Mustang, but it only shut off one hose.
If your airflow is tapering off as the blower warms up the blower will probably need to be replaced because the shaft bushing/bearing is starting to seize. The blower should have 3 speeds which are generated by adding resistance in the blower circuit. There is a resistor pack mounted in the blower housing from the engine compartment side. There are 2 resistors which are combined to get the 3 speeds and are in the housing for cooling. One of the resistors may be opening when it gets hot, though not as likely. I always have had a hard fail when a resistor goes bad.

 

[rickybobby]

I had the same problem with my 01 taurus, the air stayed cold, but the airflow would drop off slowly. if i turned off the AC the airflow slowly came back. I replaced the pressure switch and it worked great after that