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Carl’s Corner – Auto Repair Help

DIAGNOSE – A/C SYSTEM DOESN’T BLOW COLD AIR

By Carl O’Reilly

SYMPTOM SUMMARY
The air conditioning system is not cooling as expected. The air conditioning system may require an extended period of operation to reach the desired output.

USUAL CAUSE
Low refrigerant level is the most likely cause of poor cooling from the air conditioning. If there is no cool air coming from the air conditioning system, an electrical malfunction could be the cause. A defective relay, compressor clutch coil or damaged compressor are all possibilities.

DIAGNOSIS
The air conditioning system is equipped with safety switches that automatically turn the compressor off when the A/C refrigerant level becomes low. This prevents compressor damage, since the lubricant for the compressor is circulated through the system by the refrigerant. When the pressure switches are activated, power to the compressor is interrupted regardless of the position of the A/C dash switch. Recent regulations have prevented most consumers from doing the repairs. Special equipment is now used to remove the refrigerant, referred to as “evacuate” prior to opening the refrigerant system. Special leak detectors are used to detect leaks around hoses, fittings, and valves. Once pinpointed, the leak will have to be repaired once the existing refrigerant, if any, is removed.

PRECAUTIONS, TIPS, and NOTES
The refrigerant system is under high pressure at all times. During operation, the high pressure side of the refrigerant system can reach pressures of over 275 PSI. Use extreme caution when working around the A/C system. Never disconnect or vent the refrigerant to the atmosphere. Refrigerant can cause extreme frost bite or blindness if it comes in contact with your skin or eyes. Repairs to the A/C system are best left to trained service personnel using the proper test and service equipment. Repairs can be made by the consumer, however, the system should be evacuated using the proper equipment by trained service personnel prior to any component replacement. After the system is repaired, it will have to be recharged using the same type of equipment.


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30 Comments on "Diagnose Ac System Doesnt Blow Cold Air"

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3 years 4 months ago

I recently tried recharging my a/c system (5.3L chevy Silverado truck) with an “easy charge” system from my local auto parts store (attaches to the low side and press the trigger). I think I overcharged it because now the compressor clicks on for a couple seconds then off and only warm air is blowing. I bought a set of guages and an evac pump and evacuated the system, put in a new expansion valve, and tried it again, same result. The reading on the guages are LOW SIDE=high & HIGH SIDE=low. Did I f-up & need to replace the compressor/accumulator?

carl moyer
3 years 1 month ago

sure would like to know the answer to Brian’s problem as I have the same exact headache!

1 year 6 months ago

When compressor is dirty, that means it is automatically damaged. Make sure to do away with the oil leaks, and remove the dirt that might build up in the motor or the pump. When the air compressor is clean, it will be able to provide the needed temperature and also a smooth operation.

Nick
1 year 6 months ago

Your compressor brings down the suction pressure and increase head pressure which is your high. Something is wrong with your compressor bro

Brent
1 month 17 days ago

If you unplug the connector to the cannister on passenger side that is wrapped in insulation, stick a paper down to complete the circuit, it will keep the clutch engaged so the suction side, low side will take the refrigerant in, with the clutch clicking off and on it won’t except the coolant, only that second or 2 it’s engaged.

1 year 11 months ago

Due to the expansion in the air compressor there are very advanced compressor are available in the market with the low risk factor and high power facility.

1 year 10 months ago

I evacuated the system and disconnected the lines to check that the condenser isn’t plugged by blowing by filtered air through the system.

The low and high side switch works. If it has too high of a charge, the compressor won’t turn on. If it has too low of a charge, the compressor won’t turn on.

I replaced the drive belt and adjusted the tension during installation.

The central console switch(s)work.

I’m not sure if the receiver / dryer on the R/F fender well is bad or the evaporator under the dash is bad.

Brandon
1 year 6 months ago

I have a 2005 Chevy Avalanche. It is a 1500. My AC has always been a little weird. At times it would blow hot air, but would stop after the car was turned off and on. However, now it only blows ambient air. It was over charged a bit at one point, but no longer. I checked the electrical box for the AC fuses. I found out that the AC Compressor 10 A fuse will immediately pop when I turn on the AC, but air still blows out the vents.

jim
1 year 4 months ago

I have a 2008 town and country. My ac is blowing warm air. There are no leaks that I can see, I also used the dye and UV light. The compressor engages when ac is turned on. What can be the problem ?

Brittney
1 year 2 months ago

Ive replaced the conpressor and condensor and still blows very very hot. Any ideas as of why.

1 year 2 months ago

I HAVE A 1983 CHEVY K10 MY AC TRY’S TO GET COLD FOR ABOUT
2-3 MIN & THE THE HOT AIR COMES,COULD THE COMPRESSOR BE BAD
WHAT CAN I DO TO FIND THE PROBLEM

henry
1 year 1 month ago

hi i have a 1991 chevy s10 i had a certified ac technicion install all new parts in my truck i even changed the radiator thermostat water pump fan clutch i even installed two electric fans nfront of the condensor and it keeps blowing my compressers within hrs and will not blow cold air thru my vents i dont know wat else to do evben the tech cant figure out wats going oni need help

9 months 7 days ago

times when you use the word “but”, it negates everything you said before the “but”. For vary in length.A wind power turbine is vital in the production of wind power. It is in 1994

george savoy
1 year 1 month ago

Hi , My name is George I have 2003 S10 pick up Air Condition is working , I just change new Blend Door Actuator part and still blower hot air but I check Air Compressor and Condenser is working well and cold but inside truck Dash board blower hot air while AC is on ! I Cant find what is Troubleshooting ! So can u feedback me Help Please !Thanks George

Jay
3 months 1 day ago

Try The Cabin filter Under The Dashboard

Joe
1 year 20 days ago

I have a 5.3 1999 GMC 1500 Pick up
The AC blow cold for about10 minutes then blow hot. shut truck off for a while then blow cold for 10 minutes then hot. Had it recharge no change. Was told it might be the clutch kicking out when it gets hot.

albert
9 months 28 days ago

the air blows but it doesn’t throw cold air and I can’t hear the a/c turn on, on the engine e

Ganiyat Ismail-Balogun
6 months 25 days ago

My car a/c will work for a minute then stop for 5minutes then pick up again .my car is sienna 2001 .pls what can I do
.

Robert Willbee
4 months 25 days ago

I have a 2001 chevrolet silverado,only blowes ambient air
on the recycle side but vary cold air on the maximun a/c side when the a/c is on the recirculating side the accumlater has no build up of moister on it, could this be low pressure, cause it is not cooling
any help would be greatly appreciated

3 months 23 days ago

The air show sign outside that it’s getting cold but it’s want get cold on the inside……I have a 02 freightliner Columbia

Bob
3 months 14 days ago

2005 dodge pickup ac works when idling when under power the clutch kicks out
Then kicks back on after 10 to 60 seconds more so pulling a trailer

Michael
2 months 27 days ago

Hey guys & gals i have a 2003 gmc envoy XL with AC issues…. I’ve replaced the upper and lower pressure sensors/things and had the ac checked and recharged last summer and it seemed to work fine as long as it was in the driveway not moving…. As soon as we would get out moving it would Quit blowing cold air. The compressor clutch is NOT SEIZED!!!! Like i said before, i had everything checked last summer and it was all good with new sensors and ac recharge and no leaks….Hmmmmm I’m Very Confused. Please help me anyone that might have an idea or suggestion to something that i may have over looked….. You can also reply to my email [email protected]
Thanks SO SO much for any suggestions!!!

2 months 16 days ago

in my 2008 forenza suzuki, an AC compressor kit was installed. everything works, but only cool air is coming out, not cold..they checked everything about the compressor and still cant figure out why…what else could cause this problem, maybe “control valve” stuff?? please help

2 months 16 days ago

in my 2008 suzuki forenza, a new AC compressor kit was replaced, after 3 trips back to the shop, ONLY cool air comes out, not cold….any suggestions as to what else could be the problem, maybe a “control valve”?….help

Brent
1 month 17 days ago

My A/C is properly filled with refrigerant, but not getting cold air, just cool and won’t keep the cabin comfortable in this Texas heat, is it the 134a or should I have a shop put the good stuff back in, never had a problem with the 134a before till recently

Don
1 month 16 days ago

I have a 2003 GMC Sonoma compressor is working clutch is working new pressure sensor new blend door actuator
but still no cold air what do I check next?

Al Smith
1 month 7 days ago

The most common cause of compressor cycling and no cold air being produced in my experience has been an over-serviced system. An over serviced system does not have sufficient pressure differential between the high and low sides of the system. It is this pressure differential that allows the compressed gas in the high side to expand rapidly after it passes through a restricted orifice and enters the evaporator on the low side (Rapid gas expansion causes dramatic temperature drop) . The over serviced system reaches the high pressure cutout set point which cuts out the compressor after the compressor has operated for only a few seconds. The short run cycle of the compressor never allows for a pressure differential to develop and results in very little flow of refrigerant through the system. AC systems must be serviced precisely to manufacturers specifications as different systems may have different high as well as low pressure cutout set points. Try lowering the system pressure to remedy this problem (This is usually counterintuitive).

A similar problem is when compressor cycling occurs after the system has been operating normally for the first several minutes of operation. After a period of normal operation, suddenly the air goes warm and the compressor starts cutting out after a very short run cycle. In this case, the system may be contaminated with humid air. The dryer may be maxed out and the humidity is freezing up the orifice where the refrigerant passes into the evaporator, effectively clogging the system. This clog creates a rapid rise in pressure on the high side causing the compressor to cut out. With no refrigerant passing through the orifice, the area starts to warm and the “Ice clog” thaws allowing refrigerant to flow again only to refreeze after enough ice has collected in the orifice again. This problem can result in erratic AC operations where it seems to operate fine one day and not the next. Ambient air temperature and air flow around the evaporator orifice and engine temperature may be conditions that affect whether the orifice freezes up or not. To remedy this issue, have the system serviced properly by installing a new dryer and evacuating, drying and servicing the system per the manufacturers specifications.

Justin F
19 days 23 hours ago

I have a 2004 Chevy Impala 3.8. I have checked all of the fuses and relays as well as turned to center bolt on the compressor. The fuses and relays are good and the compressor turned freely. I have also checked the pressure in the system. It reads full. Is it possible the compressor is bad. Or is there anything else i can check?

10 days 20 hours ago

a/c just blows hot air but no pressuer on low side

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