AC shuts off at 120kph

**mayhem** · August 23rd, 2010 07:39 AM

I have a ford explorer 2003 4.0L, my AC shuts off at speed of 120kph but comes back upon deceleration. What could be the problem?

**RustyXIII** · August 23rd, 2010 08:46 AM

That's normal. The compressor has a protection mechanism that prevents it from spinning too fast. It happens at a certain RPM, not vehicle speed. Observe then report back.

**oj88** · August 23rd, 2010 09:12 AM

I don't think that's normal.

Most A/C compressors are rated for 10,000 RPM... I'm sure the Explorer's engine is capable of way below that. I'm thinking that it's a refrigerant pressure-related problem. System pressure increases with the RPM.

OP, try to observe the RPM gauge at the point when the compressor disengage. Try to simulate that with the vehicle stopped and in neutral and raise the RPM to see if the compressor cuts off as well.

**ghosthunter** · August 23rd, 2010 09:37 AM

Originally Posted by mayhem

I have a ford explorer 2003 4.0L, my AC shuts off at speed of 120kph but comes back upon deceleration. What could be the problem?

When was the A/C system last serviced?

The A/C filter might need replacing. If it's clogged (or some other component is clogged), your A/C system might be abnormally experiencing high pressures.

Shutting down at higher speeds might be a way for it to protect itself from damage.

**mayhem** · August 23rd, 2010 11:48 AM

i havent touched any AC components yet coz cooling is ok up to now, but it could be something else now coz i havent experienced this before even if im cruising at high speed Ac never shut off not until lately..

some say it could be the expansion valve, might be?
sorry for being noob, but where can i locate the AC filter of ford explorer?

**ghosthunter** · August 23rd, 2010 12:40 PM

Originally Posted by mayhem

sorry for being noob, but where can i locate the AC filter of ford explorer?

Specially on your Ford, no idea.

Normally it is located at the front of the engine bay, usually near the A/C condenser. It will be a metal "bottle" approximately the size of a 500mL water bottle with two metal hoses attached at the top.

**mayhem** · August 23rd, 2010 01:26 PM

is this filter the same as the accumulator?

**ghosthunter** · August 23rd, 2010 02:41 PM

Originally Posted by mayhem

is this filter the same as the accumulator?

Don't know.

The a/c filter is meant to "separate" the liquid state freon from the bubbles/foam.

Accumulator is usually something simply to temporarily store a liquid or gas before it is (often quickly) released.

**miko101130** · August 24th, 2010 09:20 AM

just a word of advice based on experience in order to help. the new models of vehicles especially of those made by ford may not use the old drier/receiver type(typically a can with sight glass). for instance the ford everest drier is inside the condenser(looks like a cloth that contains silica gel to absorb moisture and excess oil) and is housed by the round tubing to the left of the condenser. it is disposable and easily replaced not like the can type of drier.

i have also experienced the same case. i have a ford everest. back then when i was cruising at a sustain high speed of greater than 90kph the aircon seems to stop working. it doesnt give any coldness. i knew that the compressor shuts off because the engine feels lighter. when i have had my aircon system completely serviced; includes cleaning,flushing,oiling, repalcement of drier,expansion valve, i noticed that it was gone. By the way i have already replaced my compressor 3 times, 2 compressors were busted. So i browse the internet read some manuals and other informative website and i came to a conclusion that; the aircon system will shut off the compressor by disengaging the magnetic clutch if, 1. the system detects a high pressure brought about by a dirty,clogged aircon system, a defective expansion valve and a faulty thermostat. 2. the magnetic clutch itself is defective and might switch on and off(probably electrical problem). 3. there is undercharging of freon(low levels of freon, the compressor senses it and cuts off power to prevent damage to compressor).

its better if you can have your aircon checked and cleaned by a qualified and good aircon technician, your aircon system might just need a cleaning and flushing. if ever you decided to have it cleaned, insist that they do a full flushing(aircon lines/evaporator/condenser) and use nitrogen to flush out the dirt, otherwise those particles left behind might destroy your compressor.