LexBrett2

Hi All;

I own a 2006 cls500, approximately 65K miles. To my surprise this morning my heat was not working.

My first suspicion was that I blew a fuse; Saturday I installed a backup camera and I ran a fuse tap in the driver's side fuse box. I'm fairly certain one of the fuses controls the heat, so as soon as I get home today that's the first thing is for a blown fuse. Note that the blower motor itself is strong, and the AC is working too. Any suggestions are welcomed!

I also spent several hours this morning researching other possible causes for lack of heat. Apparently, failure of the heater control valve is fairly common. I found the part at Advanced Auto, and I believe (?) this is the same as the OEM part. I prefer buying OEM, but it is also nice to buy in store and return if something does not fit or goes wrong. Here is the part from Advance Auto as well as eBay:

https://shop.advanceautoparts.com/p/...chTerm=heater+

https://www.ebay.com/itm/NEW-GENUINE...FZQNlF&vxp=mtr

I also plan to use my iCarsoft MBII reader to investigate any possible codes.

It seems there is a laundry list of possible causes for heat not working, at least from my initial scan of this forum and the internet. If you all have the time, would you please point me in the right direction so I can prioritize?

Thank you all very much in advance and have a great day! Lex

LexBrett2

Apparently, sudden loss of heat is due to either low coolant, a bad or blocked heater core, the heater valve switch, or an open circuit. Here is an article that describes:

https://www.lifewire.com/car-heater-...working-534657

Any thoughts, comments, or suggestions?

LexBrett2

So yesterday I opened both fuse boxes and checked connections. Then I started my car and the heat started working. Later used my code reader and found the code in the pic below. Perhaps the heater valve is about to go bad, or I did indeed bump something leaving an open circuit allowing heat to fail. Thoughts are welcomed!

VII

The heater control valve is likely to be on the way out, I would stick to OEM as its a pain to replace.
mboemparts.com

LexBrett2

That's what I was thinking as well.
When it goes, I will buy OEM.