A/C evap. freezing up in cool weather?

[DEllerbe]

Just to see if any one else has experienced the same problem. -- My A/C cools great even on the hottest days. Although, when it's humid and cool out and I need to de-fog my windows the evaporator freezes up. Just got my cd-manual from DC and found there is a temp sensor on the evaporator coil to guard against the exact problem I'm having. Will look into it when I get in from off-shore. Anyone having a similar problem?

 

[sag2]

How do you know it is freezing up? Ice on the line, or is the air flow restricted?

 

[inarush76]

Had this happen to me on long trip in rain. Lost cool air and flow, ice about 1/4-3/8" thick on line near firewall. Shut off and let set for a while, thawed, hasn't done it since that I have noticed.

James

 

[BigCarl64]

Mine did the same thing. All the humidity down here in South Texas doesn't help.

 

[jelag]

A couple of thoughts... .



On a cold day, the freon (can I still use that term?) doesn't fully change from a liquid to a gas in the evaporator... ... there isn't enough heat there to absorb... . some of this freon is than leaving the evaporator as a liquid and turning to a gas in the line... hense the freezing of the line and the frost... either the system isn't cycling like it should. . or wasn't designed to cycle and the frost is an acceptabe by product of running the defroster in the winter... . There is a couple of fixes for this... a design change to prevent this flooding... . which costs DC money and we won't see. . or a smaller orifice in the system to allow less flow... . so you'll have limited cooling in the summer... . not good... .



So I'm guessing thats the way the engineer designed the system. .



Jim

 

[DougR]

jelag



Most of what you say regarding why they freeze is true,but unlike your home AC which is designed to not "flood" in normal conditions,your vehical compressor is extremely over sized to handle the tremendous loads in the summer. However as he pointed out the compressor is cycled with a low temp freeze stat. This is probably where the problem lies. Without it,any auto AC will freeze in minutes.

 

[DEllerbe]

Originally posted by sag2

How do you know it is freezing up? Ice on the line, or is the air flow restricted?

I have problems with both (ice and airflow slowly restricting until none).

Originally posted by jelag

A couple of thoughts... .

I also found the temp sensor in the DC manual. It is located on the evap coil to shut-off the compressor when there is below freezing condition for a period of time. Haven't checked its operation yet though, will check the next time I'm in.



On a cold day, the freon (can I still use that term?) doesn't fully change from a liquid to a gas in the evaporator... ... there isn't enough heat there to absorb... . some of this freon is than leaving the evaporator as a liquid and turning to a gas in the line... hense the freezing of the line and the frost... either the system isn't cycling like it should. . or wasn't designed to cycle and the frost is an acceptabe by product of running the defroster in the winter... . There is a couple of fixes for this... a design change to prevent this flooding... . which costs DC money and we won't see. . or a smaller orifice in the system to allow less flow... . so you'll have limited cooling in the summer... . not good... .



So I'm guessing thats the way the engineer designed the system. .



Jim

 

[DEllerbe]

Sorry about that last post I didn't mean to include my writing in the quote (accident). Here it is again:



I also found the temp sensor in the DC manual. It is located on the evap coil to shut-off the compressor when there is below freezing condition for a period of time. Haven't checked its operation yet though, will check the next time I'm in.