Cleaning A/C Evaporator

[buddrow00]

The wife drives a 2004 Limited 4 Runner (V8) with 55K miles. Every time she goes to the stealership, they tell her the A/C evaporator needs to be cleaned. My questions are:
1) How often does the A/C evaporator need to be cleaned?
2) We have noticed no problems with the A/C or the temperature of the A/C, is this just a ploy for the stealership to perform unnecessary services?
3) What happens if my A/C evaporator is dirty? What kind of performance problems can I expect?
4) I can perform some basic maintenance myself, change the oil, air filter, in cabin filter, etc, should I attempt to clean the A/C evaporator myself, or leave it up to the stealership?

Thanks.
Mr Buddrow.

 

[JeremyH]

Cleaning the evaporator coil is not something that is routinely done on a vehicle (unless there is an issue) and will take quite a bit of work to do. Even the AC in your home doesn't usually require that the evaporator be cleaned often (unless you have quite a few dogs and dont regularly change your air filters).

The evaporator coil looks like a radiator....it has a bunch of aluminum fins with copper tubing running through them and it is inside your vehicle, under the dash inside a plastic box. After you drive with the AC on during a hot day, you'll see a puddle of water under the vehicle (even after you turn it off)...this water is dripping from the evaporator coils (the drain passes through the firewall). Here is a good general description of how a refrigerant system works:
http://www.europe.honeywell.com/70_refrigeration_control/EN5B-0024UK07 R0505.pdf
When your evaporator coils get clogged and cannot cool properly, they will freeze over. You'll notice a sever reduction in cooling ability of the system.

Next time you are at the dealership you should ask them exactly what symptoms they have witnessed the lead them to believe that your vehicle's evaporator coil needs to be cleaned. My guess is that the symptoms they have witnessed are that their repair bays are empty because they just sold a bunch of new cars during that Cash For Clunkers program and nobody is bringing in their vehicles for repair.

 

[buddrow00]

Jeremy,
Thanks for the information. With the A/C still blowing cold air, I am not concerned right now.

B.

 

[JeremyH]

You are welcome. I would not be concerned either...

 

[shawnstcyr]

If you ever have to do it, there is a product out there that we used to use on semi trucks. I can't remember the name, though. The oil field trucks used to come in clogged from all the dirt and dust. It was just a foaming spray. Then we would rinse them out. I'm sure a truck parts place or your local AC repair man could sell you some.