AC Not Working - Please Help

[DVC72680]

I have a 2004 Grand Marquis and recently my AC went out and I noticed the AC Clutch was doing the quick cycle routine and never staying on constantly.

Here is what I have done so far so hopefully someone has seen this and can help.
Checked freon level and was right where it needed to be.
Checked all associated fuses and all were good.
Checked all switches in the control module, fan speeds, mode select and temp hot/cold all functioning correctly.
Checked blend door actuation by controlling temp while in VENT mode. Will go from very hot in car to cool/ambient temp.
Jumped out (paperclip) the switch on the accumulator and the clutch ran and stayed on.
I had my bro in law (mechanic) check the system with AC machine, he verified amount of freon in system and that I did not have a leak in the system.
He then installed a new accumulator and switch.
He then evac'd the entire system and then re-filled it with correct amount.
Started the car/turned ac on, ac clutch turned on and the lower pipe became very cold but cold air was not coming out of the vents.
The shop was closing so I had to leave. When I got home it started again with the clutch quick cycling and never staying on for longer than a second.

Does anyone have any ideas? It's not a freon pressure issue, I eliminate the switch on the accumulator. What would allow the ac clutch to start but then decide to shut it off? If one of the pressure switches was faulty would it let the system start in the first place or does the system only look at the switches while in operation?

I cannot get back to his shop until this weekend so any help would be greatly appreciated.

Thanks,
Don

[DerekTheGreat]

You sure that blend door is actually opening all the way? I had a 1994 Ranger and when the A/C clutch cycled rapidly it was because the system was overfilled with stuff. THe problem with that truck's system was build up of crap between the condenser and radiator. Once that was cleared away and the system was restored to the correct amount of refrigerant & oil it worked well. You said the car was refilled with the proper amount of "stuff." Does the clutch still cycle rapidly? Also, I'm a box person, not sure if these have sensors to detect when the evaporator is freezing up, so maybe that's why your clutch is cycling so much?

[86VickyLX]

If the thing is cold but the air isn't coming out of the vents. It's probably a blend door/HVAC controller issue. The automatic systems use vacuum to control the doors.

[sly]

+1 blend door actuator is probably dead and needs replacing. There is rumors that you can just loosen the dash and get it out after removing the passenger side air bag, but pulling the dash off the firewall makes getting at it much easier.

[gadget73]

Sounds like the pressure is dropping too low and cutting it out. Usually thats either a low charge, restricted orifice tube, or the blend door is stuck and not actually pushing air through the evaporator. The evaporator being totally packed up with dirt could also do it. The charge problem has already been ruled out, so we'll skip that.

You can determine what ails it with manifold gauges. Restricted orifice tube would have too-low low side pressure and too-high high side pressure. Air flow problems through the evaporator would be low on both sides.

[DVC72680]

I apologize for the "dumb" question but I just want to verify. When I put the manifold gauges on and check the pressures, will I only the possible issues when the clutch/compressor is working or is there anything I can look at while its resting/static for any further clues? Your help is greatly appreciated.

[sly]

You really need it running to figure anything out. Watch the low side. If it's dropping out immediately, you have a clog in the system somewhere and most likely the orifice tube. If you remove that and there's lots of soft mud like crap on it, the desiccant in the dryer has degraded too far. If there's any metal shavings, the compressor is taking a dump.

[DVC72680]

Put manifold gauges on and the car has been sitting for about 3 hours since it was last started. While car off the gauges read 100 for low and 100 for high.

With car started and I turn the ac on it goes into the "quick cycle" when the clutch engages the low goes down to 15 and high goes up to 140 then shuts off. As the low begins to slowly climb the high side slowly lowers, when the low reaches 30 the high side is about 110 and the clutch engages and quick cycle repeats over and over. Same PSI values each time. Currently where I am it is 75 degrees out.

Part 2 - While in quick cycle mode - If I feel the pipe that travels from condenser to the evaporator (where the orifice tube is) the pipe near the condenser is cold on the left side but warm on the right side with some sort of mounting/adjoining clip in the middle. Is that proof the orifice tube is functioning and my issue is in the condenser itself?

[86VickyLX]

From your readings and such, it sounds like it doesn't have enough charge.

[sly]

I think the orifice tube is clogged or almost clogged. Something is being too restrictive. The pressure switches are working.

The question I have is how long does it take for the low side to go from 15 back up to 30. If this is more than 3-5 seconds, something is clogged. If it's less than 3 seconds and the compressor stays on about 1 second, then it's at least low and need more refrigerant.

[DVC72680]

It takes probably between 10-20 seconds for it to climb back up to 30. The pipe going into the evaporator gets icy cold, the pipe leaving the evaporator is not cold at all/ The things in between those two points would be orifice tube, evaporator and the blend door. I believe the orifice tube is functioning based on the fact that the pipe going into the evaporator is icy cold. I believe the blend door is functioning based on if I go to VENT mode and go full hot with the knob to full cold that the air temp changes greatly. So by process of elimination my guess is that the evaporator is the issue and probably clogged. When I go to replace the evaporator I will of course do the orifice tube since it's right there and a new one is like 9 bucks. Part of me wants to replace the blend door anyway since it's 45 dollars and one less thing to worry about but from what I seen online its a giant pain in the ass to get to. Does this all make sense...Did I leave anything out or have anything incorrect?

[sly]

If the top line from the evap is cold and the bottom one not cold, this is normal and it's the orafice tube that's most likely the clog. If it's the other way around, the evap is clogged. You might be able to unclog it by back flushing it. Though replacement would be the for sure option. If you replace it, there's no need to remove the orafice tube if you haven't already.