Please help.....2012 ML350 w166 276 engine, 4 matic gas, 3.5 liter. I am getting intermittent heat blowing into cabin....sometimes will blow warmer while driving but will become cooler at a stoplight, etc.. Changed the blower motor, thermostat, a/c compressor all 1 year ago and just replaced the auxillary pump. I'm told it is my heater core but was also told about a change over valve close to or on the firewall that could be responsible for this intermittent luke warm air blowing into cabin. Any idea where this part is located on the engine and could this be the problem? Change over Valve: Part # 002-540-68-97. I don't wan't to spend another $3000 on a heater core if that is not the problem.
Junior Member
Hi Ray, I hope this will help. The part you mentioned, the changeover valve (part number 002-540-68-97), is indeed related to controlling the flow of hot coolant into the heater core. This valve plays a crucial role in regulating the cabin temperature. If it malfunctions, it can cause issues with inconsistent heating in the cabin.
Locating this valve may vary based on the specific model and engine configuration of your vehicle. Typically, it's located close to the firewall, near the heater core or in the engine compartment, connected to the coolant lines that supply hot coolant to the heater core. However, for precise information on its location in your vehicle, consulting a service manual or professional mechanic might be necessary.
Given the symptoms you're experiencing (intermittent heating issues), it's worth considering the changeover valve as a potential culprit. Replacing it could resolve the problem without having to replace the entire heater core, which can be a costly repair.
A proper diagnosis using a good scanner like the Youcanic scanner can help identify any fault codes related to the HVAC system. This might offer more insights into the exact issue, confirming whether the changeover valve or another component is causing the inconsistent heating problem.
To avoid unnecessary expenses, it's advisable to perform a thorough diagnostic check or seek professional assistance for a precise diagnosis before replacing any components. This will help ensure that the repair addresses the specific issue causing the intermittent heat in the cabin.
Locating this valve may vary based on the specific model and engine configuration of your vehicle. Typically, it's located close to the firewall, near the heater core or in the engine compartment, connected to the coolant lines that supply hot coolant to the heater core. However, for precise information on its location in your vehicle, consulting a service manual or professional mechanic might be necessary.
Given the symptoms you're experiencing (intermittent heating issues), it's worth considering the changeover valve as a potential culprit. Replacing it could resolve the problem without having to replace the entire heater core, which can be a costly repair.
A proper diagnosis using a good scanner like the Youcanic scanner can help identify any fault codes related to the HVAC system. This might offer more insights into the exact issue, confirming whether the changeover valve or another component is causing the inconsistent heating problem.
To avoid unnecessary expenses, it's advisable to perform a thorough diagnostic check or seek professional assistance for a precise diagnosis before replacing any components. This will help ensure that the repair addresses the specific issue causing the intermittent heat in the cabin.
Quote:
Locating this valve may vary based on the specific model and engine configuration of your vehicle. Typically, it's located close to the firewall, near the heater core or in the engine compartment, connected to the coolant lines that supply hot coolant to the heater core. However, for precise information on its location in your vehicle, consulting a service manual or professional mechanic might be necessary.
Given the symptoms you're experiencing (intermittent heating issues), it's worth considering the changeover valve as a potential culprit. Replacing it could resolve the problem without having to replace the entire heater core, which can be a costly repair.
A proper diagnosis using a good scanner like the Youcanic scanner can help identify any fault codes related to the HVAC system. This might offer more insights into the exact issue, confirming whether the changeover valve or another component is causing the inconsistent heating problem.
To avoid unnecessary expenses, it's advisable to perform a thorough diagnostic check or seek professional assistance for a precise diagnosis before replacing any components. This will help ensure that the repair addresses the specific issue causing the intermittent heat in the cabin.
Originally Posted by Vin_16
Hi Ray, I hope this will help. The part you mentioned, the changeover valve (part number 002-540-68-97), is indeed related to controlling the flow of hot coolant into the heater core. This valve plays a crucial role in regulating the cabin temperature. If it malfunctions, it can cause issues with inconsistent heating in the cabin.Locating this valve may vary based on the specific model and engine configuration of your vehicle. Typically, it's located close to the firewall, near the heater core or in the engine compartment, connected to the coolant lines that supply hot coolant to the heater core. However, for precise information on its location in your vehicle, consulting a service manual or professional mechanic might be necessary.
Given the symptoms you're experiencing (intermittent heating issues), it's worth considering the changeover valve as a potential culprit. Replacing it could resolve the problem without having to replace the entire heater core, which can be a costly repair.
A proper diagnosis using a good scanner like the Youcanic scanner can help identify any fault codes related to the HVAC system. This might offer more insights into the exact issue, confirming whether the changeover valve or another component is causing the inconsistent heating problem.
To avoid unnecessary expenses, it's advisable to perform a thorough diagnostic check or seek professional assistance for a precise diagnosis before replacing any components. This will help ensure that the repair addresses the specific issue causing the intermittent heat in the cabin.
thank you! Best information yet! The problem is the change over valve will not have fault code attached I'm told! Plus, where in the engine is it... cannot find it for the life of me… Even even ask the mechanic and they cannot locate it… Next stop might have to be a Mercedes dealer for dollars $$$
Newbie
Does my 2019 GLS 550 have this change over valve near the firewall or should I assume that this bead issue from the expansion tank is the issue by getting into the coolant and clogging up my heater core and other pipes etc.
Should I remove my coolant tank and visually inspect for missing beads per the image earlier in this thread?
Thanks.
Should I remove my coolant tank and visually inspect for missing beads per the image earlier in this thread?
Thanks.
