A/C recharge - need some QUICK answers....

[PDoyle]

Help! My a/c didn't work. I recharged it...

Now it only works at idle and not while driving in gear. It will work in P and N... Not D... You can drive for a while, and while coasting out of gear and it will start to work.

Anybody else have this problem????? :-\

 

[Beowulf]

Pat,

Just a guess here but you might try replacing the belts with new Toyota belts. Mine did something similar right after I got the truck. No belt squeal but, with a bright light shining on the A/C clutch, you could see it slipping. I put on new belts and its been 3 years with no problem.

-B-

 

[PDoyle]

But, when you rev the engine up in "N" the compresser still works, and blows cold air.

Seems like a sensor or something.

 

[Beowulf]

Are your belts new and properly tensioned?

-B-

 

[e9999]

sure you didn't overcharge it?
E

 

[PDoyle]

What do you mean by over charge?

 

[malcolm]

By the way, how did you charge it? What sort of refrigerant does it take? I need to do this too.

 

[PDoyle]

ok, the belts are tight. It isn't over charged.
The a/c works, so it isn't the condenser .
Has anyone replaced the a/c amplifier?

 

[Rich]

R12 or R134a?

Before you added refrigerant what did you observe in the sight glass with engine running and AC on max?

Before you added refrigerant what were the high side and low side pressures with engine running and AC on max?

After you added refrigerant what did you observe in the sight glass with engine running and AC on max?

After you added refrigerant what were the high side and low side pressures with engine running and AC on max?

 

[xl715]

When you say it doesn't work in drive, do you mean the compressor actually shuts off when you put it in drive? Or does the vent temp just rise? If the compressor is still cycling on and off while in drive then I need to know high and low side pressures, ambient temp (temp around the truck while testing), and vent temp with A/c on, recirc and windows up. Let the vehicle stabalize (run for 10 minutes like stated then take readings just before the compressor cycles off (the pressures should be at there highest and lowest).
With all this info can give you an acurate diognosis of whats going on inside your A/C system.

 

[e9999]

you can tell easily when the compressor is working by grabbing the suction and discharge lines (the 2 big ones attached to the top of the compressor) -watch the fan!- and feeling if they are cold and hot respectively. If so, it's working.
E

 

[PDoyle]

A/C works until goes into gear. Thats it. It blows cold.
turns the compressor on and off. In park it works,
in drive it will not.

 

[PDoyle]

any more ideas, guys?

 

[RavenTai]

[quote author=PDoyle link=board=2;threadid=16299;start=msg157096#msg157096 date=1084557847]
A/C works until goes into gear. Thats it. It blows cold.
turns the compressor on and off. In park it works,
in drive it will not.
[/quote]

Do you mean the compressor turns in park but disengages in drive?


[quote author=PDoyle link=board=2;threadid=16299;start=msg157117#msg157117 date=1084559282]
any more ideas, guys?
[/quote]

if you could provide all the info asked for in the above posts you would get a better answer

 

[PDoyle]

Yes, exactly, the compressor works in park and "N".
But, when you put it in "D" it will not work. The compressor, when you put it in drive disengages.

 

[ppc]

Sounds to me like it could be one of the wiring harness problems occurring when the engine rotates when put in gear. What happens when the motor is revved in park? What happens when its put into reverse?

 

[PDoyle]

In park, it blows at 42 degrees. Reverse no A/C...

 

[Rich]

Pat,

If you don't have the equipment necessary to measure the high and low side pressures and knowledge how to do so and interpret the results, I suggest that you take your truck to an AC shop. You are risking the cost of replacing the compressor and other components that collect debris by playing around.

Rich

 

[mabrodis]

If the a/c compressor is actually disengaging then you need to figure out why. There is a wire that controls the clutch on it, I'm guessing if you measure voltage on that, when it shuts off the voltage goes away. However I haven't looked at mine recently but probably a 2-prong connector, power and ground, maybe the ground is going away? Have a volt meter on the positive and a good ground with your meter to verify that.

My guess is with the sensor, the a/c compressor will not kick on (and thusly will probably kick off) if a pressure sensor tells the ECU there is no freon in there. So that sensor might be bad or the electrical wires to that sensor are getting jiggled and shorting or coming free. I think the sensor is above the drier which is directly below the battery, just a inline electrical thing in the aluminum piping near the sight-glass.

Good Luck...

 

[RavenTai]

if the clutch is turning off than it is quite possibly and electrical problem but still not necessarily there are many valid reasons the truck would turn the AC off without an electrical failure, here are some tidbits from my 96 LX ewd, it has the auto AC but perhapses the AC clutch control is the same/similar?

"5. AIR CONDITIONING OPERATION
THE A/C AUTOMATIC AMPLIFIER RECEIVES VARIOUS SIGNALS, I.E., THE ENGINE RPM FROM THE IGNITER, OUTLET TEMPERATURE
SIGNAL FROM THE A/C AMBIENT TEMP. SENSOR, COOLANT TEMPERATURE FROM THE A/C THERMISTOR, ETC.
WHEN THE ENGINE IS STARTED AND THE A/C SW IS ON, A SIGNAL IS INPUT TO THE A/C AUTOMATIC AMPLIFIER.
AS A RESULT, THE GROUND CIRCUIT IN THE A/C AUTOMATIC AMPLIFIER IS CLOSED.
AT THE SAME TIME, THE ENGINE CONTROL MODULE DETECTS THE A/C MAGNETIC CLUTCH IS ON AND THE A/C AUTOMATIC
AMPLIFIER OPERATES.
OPEN DIRECTION TO AVOID LOWERING THE ENGINE RPM DURING A/C OPERATING.
IF THE A/C AUTOMATIC AMPLIFIER DETECTS THE FOLLOWING CONDITIONS, IT STOPS THE AIR CONDITIONING.
* THE TEMPERATURE AT THE AIR VENTS IS LOW.
* THERE IS A MARKED DIFFERENCE BETWEEN THE COMPRESSOR SPEED AND THE ENGINE SPEED.
* THE REFRIGERANT PRESSURE IS ABNORMALLY HIGH OR ABNORMALLY LOW.
* THE ENGINE SPEED DECREASES.
* RAPID ACCELERATION OCCURS."

there are a 3 relays, 4 switches and the AC amp in the path of the AC compressor clutch any one gets veto rights on compressor operation, you need to find out witch one is killing the clutch that will narrow it down

the only one I can see that would change with gear position is the starter cutout relay that turns the compressor off during crank for some reason it gets the crank signal through the park/neutral position switch, if it was damaged somehow and was to send power to the crank cut relay when moved out of park/neutral it would kill the compressor (crossed wire? Shorted switch), to see if the start cut relay is your problem (if you even have such a relay in your 94) bypass the relay with a jumper on the contact pins and see if it the compressor works in drive, or check if you have voltage on the coil pins in drive, it is a noramlly closed realy powering the coil opens the contacts, you will need a 94 ewd to find the relay and the right pins,

if that is not it next I would look at pressures switch, short the two wires, if the AC now works the switch is not happy with the pressure (either to low or to high) not sure how gear selection comes into play with pressure?, it is the next possibility in line

if that is not it keep jumping all the switches/realys until you find it