A/C issue

[paulofto]

I've done a few searches and I have not been able to find anything regarding a problem I am having.

2003 Boxster S with auto climate control.

When I first turn on the A/C it blows cold and gets the temperature down but after awhile the blower slows down and the air warms up even if I manually move the blower speed up. If I press the snowflake and turn off the A/C, the blower speeds up and cooler air starts to come out. I then wait till the cool air warms up while the blower blows high and then depress the snow flake again. The A/C come on fine, cools the air, and the cycle starts again.

Vent temperatures are very cold down to 32 F and the sensor intake on the dash left hand side gets down to the set temperature on the climate display but then slowly moves up as the blower slows.

Has anyone experienced a similar issue. It is almost as if the system is freezing up and air can't flow until it thaws and air is able to pass.

I hope my problem description makes sense. Any thoughts?

[thom4782]

Best guess poor airflow over the evaporator. When this happens, ice can build up and restrict airflow out of the vents. After the ice melts, the airflow and cooling works once again, How long since you popped in a new air filter up by the expansion valve. When you pull it out, check to see if you can see anything else obstructing the airflow. The other possibility is that the ac system isn't properly charged. IIRC, normal vent outlet temperature is more like 40 to 45 degrees. It the evaporator gets too cold, it may also experience icing.

[rexcramer]

How long does it take for the air flow to slow? The first thing that comes to mind is your system may be low on Freon. If the level is too low, than the evaporator temp is below freezing and any condensation will be frozen onto the coil. High humidity makes it worse. Probably need to have somebody put gauges on it to verify. You may or may not have a leak. Some systems just need to be topped off every few years.

Some A/C systems have problems with the mixing boxes. The diverting door is covered in foam. The foam degrades over time and blows out of the vents into the cabin. You end up with a mixing of hot and cold with no way of controlling the temp. You will know when this happens.

[paulofto]

Thanks guys. I think low freon might be the issue and the condition is worse when the humidity is high as it has been around here lately.

I'll take it in to get checked and topped up. Hopefully that cures it, if not, I'll have to do some further trouble shooting.

PS, new cabin filter 3 weeks ago and I did check to make sure all the flaps and airflow worked by adjusting cooling, heat, etc. All the mechanical aspects of airflow work.

[jsceash]

Did you check to see if both your front radiator fans come on at low speed when you turn your AC on. They should also turn to high intermittently as the system heats.

[paulofto]

Okay, had an a/c guy look at the issue. Freon level is fine but it appears the expansion valve is not working quite right. I've ordered one from Rock Auto (about $21.00 CDN plus 11.00 shipping. The a/c guy will install once it arrives.

Hopefully this cures it.

[paulofto]

Success. New expansion valve from Rock Auto arrived yesterday. A/C guy swapped it out, refilled with R134a, A/C now works like it was intended.

Cost CD$ US$
Parts $33.72 $25.92 delivered to my door
R134a $60.00 $46.12
Labour $40.00 $30.74
Total $133.72 $102.78

Considering the Porsche Dealership quoted me $120 CD$ for the part & 2 hours @ $160.00 an hour installation PLUS the recharge of R134a at who knows what price, I think I got off pretty cheap.

[rexcramer]

Excellent news.