HELP! AC not blowing cold/bad idle

the98stang

the98stang

Active Member
Aug 12, 2005
2,408
0
47
Clovis, CA
#1
So whenever I turn the AC on (doesn't matter what position) the idle jumps from 1000-1500. It is very consistent. The air is not cold at all either. I looked at the AC condensor clutch, and it's not moving at all (when I have the air on). Could this be the cylcling switch? I thought it needed a recharge, so I bought a can of R134a . The crappy gauge said the pressure was at 150psi (lower AC line). The gauge was in the red, so I didn't put any freon in the system. So what should I do? I don't want to take it to a shop yet. Thanks for anyhelp.

Tanner
 

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#3
OK so I spliced the cycling switch wires together to short the switch, and low and behold, the AC blew ice cold and the idle stopped jumping. So I'm pretty sure I need a new switch. But there's two parts to the switch (one that male/female) so do I need both? Thanks ...

Tanner
 
#4
For those of you that want to know, these are the 2 Motorcraft part numbers for the cycling switch assembly:

MOTORCRAFT Part # YH1462

MOTORCRAFT Part # WPT169

About $30 shipped from http://www.trademotion.com/partlocator/index.cfm?siteid=214290

View attachment 402880
The AC cycling switch is located on top of this cylinder (where the arrow is pointing). It's on the passenger side closest to the firewall. Thanks to SVTtech for the picture!
 
#7
Sorry, I knew the answer but just returned tothe boards, If it is a factory switch you can put a small allen wrench in the end of it and adjust it(I forget the size) That would save you a few $$
 
#11
Well I got the new switch installed, but the problem is still there. The idle still jumps with the AC on, but it doesn't happen as much as before. The AC is cold. The AC compressor will cycle on and off, probably once every 20 seconds. I also noticed the fan was running :shrug: . Maybe it just has low coolant and a leak somewhere. Is there anything else I can do before taking it to a shop? Thanks.

Tanner
 
#13
The A/C cycling switch (dual function switch) will engage the compresor clutch at 21-23 PSI and disengage the clutch at 43 PSI. That's the low side of the system. The low side pressure should be right at the ambient temp outside. So if it were 75° the low side should be right around 75 PSI no higher. If the low side gets over 140-150 PSI, the DF switch will disengage the A/C clutch. The high side clutch cut in/close is 220/280 PSI.

If you can get your car on a scanner that has the ability to read the A/C sensors. Then you can look at the pressures. If the high side and low side are equalized (pressures very close) the most common cause is the expansion valve/orifice tube. The expansion valve serves as a check valve between the high side and low side and it's not uncommon for them to fail.

It's always a good idea to replace the accumulator/drier if you have to replace the expansion valve/orfice tube.
 
#14
Unfortunetely the only scanner I have is my Xcal, and I don't believe that can read AC pressure.

I'll probably just have the car tested for leaks and have it recharged. Hopefully the clutch isn't going out on me.
 
#15
the98stang said:
Unfortunetely the only scanner I have is my Xcal, and I don't believe that can read AC pressure.

I'll probably just have the car tested for leaks and have it recharged. Hopefully the clutch isn't going out on me.
Click to expand...

Usually when the low side pressure is as high as you mentioned (150+) that is almost a sure indicator that the expansion valve/orifice tube has failed. Looking for leaks and/or evacuating and recharging the system would not fix this problem.

Another thing that can cause this is excessive head pressure on the compressor. This can be caused by improperly operating cooling fans, clogged condenser, clogged radiator, etc. It wouldn't hurt to make sure your cooling system is healthy.

But since your low side is that high, I'd bet my next paycheck that it's your expansion valve/orifice tube.:D
 
#16
LaserRed01GT said:
Usually when the low side pressure is as high as you mentioned (150+) that is almost a sure indicator that the expansion valve/orifice tube has failed. Looking for leaks and/or evacuating and recharging the system would not fix this problem.

Another thing that can cause this is excessive head pressure on the compressor. This can be caused by improperly operating cooling fans, clogged condenser, clogged radiator, etc. It wouldn't hurt to make sure your cooling system is healthy.

But since your low side is that high, I'd bet my next paycheck that it's your expansion valve/orifice tube.:D
Click to expand...

Would I have to evacuate the system to change the expansion valve/orfice tube? Where are these parts located?
 
#17
yes you would have to evac and recharge the system to replace the orifice tube, it is located in the line after the acumulator and before the evap core, it's the bottom line

I have been offline for several days, after I get back tonight I will try and help out some more.. I have a lot of catching up to do on here LOL
 
#19
It's located between the condenser to evaporator core A/C line. The accumulator is on the low side/suction A/C line that runs between the evap core and the suction side of the compressor.

The EV/OT is next the evaporator bulkhead. And yes you will need to have the refrigerant evacuated and re-charged.

If you go to the dealer, don't let them do a half ass job. Make sure they pull a 30 inch vacuum for AT LEAST 45 minutes. I've seen so many techs do the R&R of R-134a totally wrong. It wouldn't hurt to ask the dealership if they have a RRR - Refrigerant Recovery and Recycling (HVAC) certified tech. A totally evacuated system should take right at 34oz. I'd recommend repolacing the accumulator as well. 10 bucks for the accumulator and 5 bucks for the EV/OT.

They need to also measure the amount of PAG oil that cam out of the old accumulator and put back an equivalent amount into the system.
 
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