EATC codes 051 and 053

[Super-Merc]

Good Morning,

The other day after praising my 2003 MM's climate control for a nearly flawless operation in Florida, naturally it failed. It now blows full heat when the engine is warmed up. My first thought was the blend door actuator but I have codes 051 and 053 when running the EATC test. I replaced the O rings earlier this year when the defrost was the only function. The AC works until the thermostat opens then goes full hot. I can't find anything on code 053 and what should I do with the 051? Thanks for your help,
Rob in North Florida

[fastblackmerc]

Good Morning,

The other day after praising my 2003 MM's climate control for a nearly flawless operation in Florida, naturally it failed. It now blows full heat when the engine is warmed up. My first thought was the blend door actuator but I have codes 051 and 053 when running the EATC test. I replaced the O rings earlier this year when the defrost was the only function. The AC works until the thermostat opens then goes full hot. I can't find anything on code 053 and what should I do with the 051? Thanks for your help,
Rob in North Florida

053 EATC (Hard) Self-Test Fault = A/C Solar radiation sensor open circuit.

051 EATC (Intermittent) Run-Time Fault = A/C Solar radiation sensor open circuit.

Looks like it could be the solar radiation sensor, the EATC or a wiring issue.

I'd think it would be the EATC

[Super-Merc]

Thank you for the information, which item should I start with? Where is the solar radiation sensor?

[SC Cheesehead]

Thank you for the information, which item should I start with? Where is the solar radiation sensor?

If you can find someone with a spare EATC, that would be the easiest item to troubleshoot as you could just swap out and see if that corrects the problem.

I'm thinking the solar radiation sensor is mounted on the front of the PATS flashing light, but FBM or others should prolly confirm that.

[fastblackmerc]

Thank you for the information, which item should I start with? Where is the solar radiation sensor?

I believe its the sensor in the top of the dash on the left side.

[Super-Merc]

Again, thank you for the quick responses. Has anyone heard of this sensor causing this problem? I am going to try and find another EATC to slave in and test it. To me, it sounds like the dreaded blend door actuator.

[fastblackmerc]

Again, thank you for the quick responses. Has anyone heard of this sensor causing this problem? I am going to try and find another EATC to slave in and test it. To me, it sounds like the dreaded blend door actuator.

Don't think it would be he sensor, that is why I suggested the EATC.

Running the self-test should give you an 024 code if it's the blend door actuator.

[Glenn-ho]

wtf why not post what fixed it