Burning Smell

It got pretty hot here last weekend. I turned on the a/c for the first time since last summer and it barely worked. I suspected a low refrigerant charge so I hooked up my manifold gauges and took a reading. Sure enough the high and and low side pressures were down so I recharged the a/c as normal. Once charged the pressure readings looked good.

However, it still is not cooling as it should. Since the pressure readings are good I'm assuming the a/c is working normally. However now I'm noticing a burning smell which gets strong as the car warms up and the HVAC is turned to hot air. (kind of smells like burning dust). I have been using the heater just before recharging the a/c and did not get any smells.

I'm guessing there is some stuff stuck inside the evaporator and or the heater so I guess I'll have to take it apart and clean.

Any ideas on what this might be.

It got pretty hot here last weekend. I turned on the a/c for the first time since last summer and it barely worked. I suspected a low refrigerant charge so I hooked up my manifold gauges and took a reading. Sure enough the high and and low side pressures were down so I recharged the a/c as normal. Once charged the pressure readings looked good.

However, it still is not cooling as it should. Since the pressure readings are good I'm assuming the a/c is working normally. However now I'm noticing a burning smell which gets strong as the car warms up and the HVAC is turned to hot air. (kind of smells like burning dust). I have been using the heater just before recharging the a/c and did not get any smells.

I'm guessing there is some stuff stuck inside the evaporator and or the heater so I guess I'll have to take it apart and clean.

Any ideas on what this might be.

The first place I would look for a burning smell is the compressor belt and clutch. Should be easy to check should engage when on disengage when off. Try to isolate the smell to the ac system ie should be there when on never when off assuming the clutch checks out. A slipping AC belt and/or clutch may give you the smell combined with poor AC performance. Next I would sniff carefully if it is a burning smell the heater motor is capable of burning out dust if a musty smell check your AC evaporator vent tube which will smell more musty than like burning. Also I assume you know how to use the gauge set properly ie adjust for ambient and not contaminate the 134a with air slugs from the tubes etc. as contamination and overfilling can lug the compressor creating a slipping belt and poor performance. This form has helped me with several AC problems. Good Luck
http://www.acsource.net/acforum/viewforum.php?f=1&sid=8ebab7f9e7c3ff20e5a10326d219d7b1

Thanks for the reply. I have ruled out things like a belt or compressor clutch - only because that smell is not present insde the engine bay. I will take the blower out and try cleaning out the evaporator and see if that helps.