Defrost Quits Blowing (due to freezing AC coils)

[Vipera Russelli]

A post on a dripping AC reminded me of my own defrost and AC problem...

If I run my heater on defrost in winter or in the rain, within half an hour at the most the AC coils turn into a block of ice and since all air (hot or cold) passes through these coils, the defroster quits blowing air altogether (hot or cold). When this happens, putting your hand below the glove box is like touching an ice box. I've found that I can defrost the coils, or prevent them from freezing in the first place, by periodically (about every ten minutes) running the hot air on recirculate for a few minutes (which is not an option for defrost). This is a less than ideal fix because it perpetuates the problem—recirculating the air requires that I quit defrosting, increases the humidity within the car due to the condensation resulting from the thaw, which quickly increases the need to use the defroster, which results in more freezing, and so on. It's a serious safety issue due to decreased visibility and constant hassle at times, and it’s not a problem that is easy to reproduce at the dealership given that you have to run the car for a while and the outside temperature and humidity have to be within a certain range. Nevertheless, I've had the AC controller replaced based solely upon my description of the problem, but the problem remains.

Anyone else have this issue or one like it? Anyone have any ideal what is going on and how it might be remedied? Thanks!

 

[TedK]

Sometimes, just using a higer fan speed will solve this problem. What part exactly did the dealer replace? The A/C low pressure switch mounted on the accumulator is responsible for preventing evaporator fin freezing. This switch can be replaced without discharging the system.

 

[redsrt03]

Russell,

Didn't you have to have your car flatbedded a couple of times when it was brand new? (or am I thinking of somebody else). I want to take my viper for a 2100 mile road trip this summer but all of the loud clanking tells me my diff/tranny/something would probably not make it.

Why can't the VCA as a group put some pressure on the SRT people to figure out some solutions to all of these very real and ridiculous quality problems in a limited edition 85K car?

 

[GTS Bruce]

Use a higher fan speed