T
The Magician
Guest
I'm getting warm air from the ac unit. Filled with new 134 A and the ac unit shuts off every minute. The guage reads up to 70 and recycles off and down to 30. Wha would cause this? Thanks. 98 Chev. van.
Jim Martin
Supportive Member
If I remember correct there is a cabin filter in the inside under the dash or behind the glove box.....
Normally when they get clogged ..the unit cant breath and won't cycle.....
Normally when they get clogged ..the unit cant breath and won't cycle.....
T
The Magician
Guest
Jim it recyles offf and on every minute.
Lee Stockwell
FOJL
If the filter Jim mentioned is clogged the thermostat will think the truck is already cold and cycle the compressor off.
Does it do it in "recirculate" mode?
Does it do it in "recirculate" mode?
T
The Magician
Guest
Lee i beleive it does.
dgardner
Moderator
Jimmy,
A suction pressure of 30psi when the compressor is engaged indicates an evaporator temperature of 35 deg, a little too low. Either the system is low on charge, or like Lee says you have no airflow across the evaporator coil, or the orifice tube is plugged. If the fan is blowing air out the registers, you need to check the air doors to be sure they are directing air across the evaporator coil and not the heater core (or if the heater has a vacuum water valve, that the valve is closed).
Without a high side pressure reading, hard to tell if you have a plugged orifice tube or not. A plugged tube will cause a very high discharge reading, and could be causing the compressor to cycle, if the system has a high pressure cutout switch (some do not, they just have a burst disk that pops).
Recommend you do NOT try adding any more refrigerant until you get a high-side reading.
A suction pressure of 30psi when the compressor is engaged indicates an evaporator temperature of 35 deg, a little too low. Either the system is low on charge, or like Lee says you have no airflow across the evaporator coil, or the orifice tube is plugged. If the fan is blowing air out the registers, you need to check the air doors to be sure they are directing air across the evaporator coil and not the heater core (or if the heater has a vacuum water valve, that the valve is closed).
Without a high side pressure reading, hard to tell if you have a plugged orifice tube or not. A plugged tube will cause a very high discharge reading, and could be causing the compressor to cycle, if the system has a high pressure cutout switch (some do not, they just have a burst disk that pops).
Recommend you do NOT try adding any more refrigerant until you get a high-side reading.
joeynbgky
Supportive Member
The system can kick on and off if there is to much Refrigerant and it can also do it if there is not enough.. I would have it drained, weighed and the right amount put back in.. better yet, take it down to Midas and have them give youa free estimate, your know whats wrong with it, then fix it yourself. 
Jim,
Sometimes the compressor clutch becomes worn (not worn out). The compressor pulley is spinning and then you turn on the A/C and this magnetically sucks the clutch plate into the pulley and it spins. Over time the stationary clutch plate hits the spinning pulley it causes wear and the clutch plate becomes thinner. As the clutch plate becomes thinner the gap between the pulley and the clutch plate increases. With the A/C off the gap should be .020-.030. Check it with a set of feeler gauges. If it is worn you might find a gap from .050-.070 in size. As the gap gets too wide the small magnetic force that engages the clutch (sucks it into the belt pulley) can't keep it sucked in. So your clutch is kicking in and out so you get cold air, then hot, then cold etc.
Very easy (free) fix. I just fixed mine about 1.5 weeks ago. Takes about 10 minutes and you dont need any a/c gauges or special tools. A 1/4" ratchet and socket.
In the center of the clutch plate (pulley) there is a small bolt (8mm I think). Remove this bolt. When you try to break the bolt loose the pulley will want to turn so leave the engine off but turn the key to the accessory position and turn the A/C on. This will engage the clutch and suck into the pulley locking it in place so you can loosen it. After loose turn key off. Pull the clutch straight out. Should come out easily. Either on the end of the clutch plate shaft or in the hole the shaft goes into is a shim (small washer). Remove it. Put the clutch plate in (no master spline) and re-install the bolt. Turn key on again without starting engine and turn A/C on to lock pulley, and torque bolt. Turn key off to dis-engage the pulley. Check gap between the clutch plate and the belt pulley again. It will probably be between .020-.030. Start engine and turn A/C on and it should work fine. You will not loose any freon during this fix. While clutch engaged and spinning, one line coming off the compressor should be hot and the other should be cold. If that is the problem, narrowing the gap will fix the clutch kicking in and out and you should have no more problems. If with the clutch spinning the two lines are not hot and cold then the compressor will need replaced.
Good Luck,
Mac
P.S. Most garages will want to replace the clutch or compressor when not needed because they don't know about the shim (spacer). The clutch alone around $150.00 and compressor could be several hundred.
Sometimes the compressor clutch becomes worn (not worn out). The compressor pulley is spinning and then you turn on the A/C and this magnetically sucks the clutch plate into the pulley and it spins. Over time the stationary clutch plate hits the spinning pulley it causes wear and the clutch plate becomes thinner. As the clutch plate becomes thinner the gap between the pulley and the clutch plate increases. With the A/C off the gap should be .020-.030. Check it with a set of feeler gauges. If it is worn you might find a gap from .050-.070 in size. As the gap gets too wide the small magnetic force that engages the clutch (sucks it into the belt pulley) can't keep it sucked in. So your clutch is kicking in and out so you get cold air, then hot, then cold etc.
Very easy (free) fix. I just fixed mine about 1.5 weeks ago. Takes about 10 minutes and you dont need any a/c gauges or special tools. A 1/4" ratchet and socket.
In the center of the clutch plate (pulley) there is a small bolt (8mm I think). Remove this bolt. When you try to break the bolt loose the pulley will want to turn so leave the engine off but turn the key to the accessory position and turn the A/C on. This will engage the clutch and suck into the pulley locking it in place so you can loosen it. After loose turn key off. Pull the clutch straight out. Should come out easily. Either on the end of the clutch plate shaft or in the hole the shaft goes into is a shim (small washer). Remove it. Put the clutch plate in (no master spline) and re-install the bolt. Turn key on again without starting engine and turn A/C on to lock pulley, and torque bolt. Turn key off to dis-engage the pulley. Check gap between the clutch plate and the belt pulley again. It will probably be between .020-.030. Start engine and turn A/C on and it should work fine. You will not loose any freon during this fix. While clutch engaged and spinning, one line coming off the compressor should be hot and the other should be cold. If that is the problem, narrowing the gap will fix the clutch kicking in and out and you should have no more problems. If with the clutch spinning the two lines are not hot and cold then the compressor will need replaced.
Good Luck,
Mac
P.S. Most garages will want to replace the clutch or compressor when not needed because they don't know about the shim (spacer). The clutch alone around $150.00 and compressor could be several hundred.
B
Bill G. Martin
Guest
OK, now, why not replace the shim/washer to keep tolrances correct and thus preventing a drag and premature wear on the pulley??
Bill in central Florida
Bill in central Florida
The clutch is already worn that is why the gap has increased. Some have more than 1 shim, so do one at a time or put a thinner washer in. Mine has 203000 miles and only had 1 shim and it had to come out to get the proper clearance. Taking the shim out does not cause it to drag, there is still clearance between the pulley and clutch plate until you turn on the A/C. Then it is magnetically drawn into the spinning pulley and spends at the same RPM as the pulley. The wear is caused by the stationary clutch hitting the spinning pulley. Nothing you can do about it is that's the way it is designed. As the clutch plate gets thinner from repeated contact with the spinning pulley the gap increases. By removing the shim the clutch is moved closer to the pulley and brings it back into the proper clearance.
