Ok I know this is a boat forum but there are some pretty sharp individuals out there and I am stumped. I have a 96 Explorer that after an hour on the interstate air quits coming out of the vents. You can hear the blower motor running full blast but no air movement at all. If you shut off the AC for 15 minutes it works fine again for 30 minutes. But unfortunately 15 minutes with the windows down you are cooked! Its like the door that controls heat and cold is closing. Any ideas would help.
It sounds to me like the part under the dash (condenser or evaporator...I never can keep those straight) may be freezing up. The same thing happens on my girfriends Honda Accord. Is it really humid where you live? I can tell when hers is about to stop working because a few flakes of snow start poofing out. I click it over to fresh versus recirc, and the problem seems to fix itself. Just a thought...
Skeep
First, some road map stuff. There are two aluminum tubes coming out of your firewall from the evaporater coil. The liquid side is the tube connected to the condenser in front of the radiator. The suction side (low side) goes to the compressor (it's cold when the A/C is running). The hot gas line (high side)goes from the compressor discharge to the condenser coil.
Yep, evaporater is freezing up. Couple of things going on that can cause it.
One, system is undercharged. The low pressure results in a corresponding evaporater temp below 32 degrees and the condensate water on the coil freezes.
The other, the system should have a low pressure cutout switch. The charge could be OK, but the switch isn't working. At highway RPMs the compressor turns faster, has more suction, and that takes the evaporater pressure below the freezing level like the above. If the switch is working right, it should cycle the clutch at a certain pressure to prevent freezing.
Either way, you have to visit your friendly mechanic. EPA regs and all that. Back in the good old days I did all the repairs on my auto A/C, but reclaim units and all the rules blew that.
Hope this helps.
You can replace the cycling switch yourself,you do not need to pull the freon out.Look at the black canister in front of the heater case on pass. side,simply disconnect the switch and unscrew it.It has a schrader valve(like a tire)and only a slight hiss will come out.Screw on another one and try out.Switch is about $30.A more common problem on these Explorers is the temp. door breaks where the actuator motor splines into it.Open the glove box door,pinch the tabs on glovebox and let it swing down.Take a long screwdriver and pry up right under the edge of the white blend door motor.It will unsnp.You need to raise it up about an inch and then set it aside.Get a small mirror stick and look at the part where the actuator shaft goes into it.If it is cracked,you will need to replace the heater case which is best done at a Ford dealer,it's not cheap as dash,concole and underhood case must be removed.
I never thought of that. Kick myself as I know better. I have seen that happen on home units but that never crossed my mind. I will put the gauges on it when I get home. I am the backyard mechanic who installed a new evaporater when it sprang a leak last year. Thanks guys I new you would come through.
1bigjim-With gauge connected to low side fitting on accumulator, compressor should cycle off at 22.5 psi and on at 45-46psi.Keep me posted,I will walk you through any repair needed.
HP350SC:
It has a schrader valve(like a tire)and only a slight hiss will come out.Screw on another one and try out.D'oh! I forgot there is a schrader valve in the connection. Makes things a lot easier.
A long time ago I was quoted some outrageous price to repair the A/C in my pickup and I responded by purchasing a manifold gauge set, a vacuum pump, and a big azz book. It has paid off many times over.
On Sunday I was checking out the A/C at a rent house I bought a few months ago, and found the evaporater coil had the dreaded black "goo" syndrome. Nice of the inspector to miss it, he still got his money. A pain in the ass cleaning it for sure, but still better than a $300 service call.
All of you guys that are motorheads should try to learn more about air conditioning. If you can build a honker for your boat then fixing an A/C unit is no big deal.
[ August 05, 2003, 08:51 PM: Message edited by: rrrr ]
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