[ILvolter]

Hi everybody,

Been lurking around for the last few days since I bought my Volt. Didn't want to make my first post a problem post but I need some help.
I took delivery of my 2018 Volt on 11/30. The next day i was running around and a Service Heater message came on. I cleared the message and went to the dealer. They looked at it and said there are no codes and to see if it comes up again. This morning the drive was downright dangerous. I left in EV mode and the windows began to fog. Turned max defrost on had temp at HI and medium fan and continued to drive. 5 to 10 miles later the windows were still slowly getting worse and no heat only cold air from the system. Double checked my settings and defrost is lit and max is lit and temp is at high. I put the car in Hold mode and watched the coolant temp rise and when it hit 120's I had heat and my windows cleared. Put car in EV mode again and almost instant cold air. Continued to drive in EV and never got any heat. Ended up driving rest of way to work in Hold mode. Did some searching and I think my EV heater is not working. I noticed in EV mode when I am at a stop the total power is only 0.5kW with max defrost on. Am I mistaken or is there supposed to be more of a draw when heat is on? Anyways its back at the dealer and they gave me a loaner and have it overnight to diagnose. The service heater message never came on again after the first time.

 

[obermd]

Hopefully the dealership is leaving it outside and having their tech look at it first thing in the morning. For future reference, don't clear check engine lights as a lot of dealerships can't diagnose themselves out of a paper bag without the code that triggers the light.

 

[jcanoe]

When an issue like this happens it is best to pull over when you can safely stop, park the Volt. Press the Blue Onstar button. Ask the OnStar representative to run an on-demand diagnostic test of your Volt. If the test returns any error codes these will be made available to the dealer's service department. Ask for the case/ticket number so you can provide this to the dealer's service department.

It could be a number of things that are the source of the problem. The electric heating unit, when operating, will typically draw between 3 and 7 kW from the battery. 0.5kW is just the Volt powered on.

 

[snic]

They looked at it and said there are no codes

GM's dealer service departments have become complete slaves to "codes". Rather than actually test the heater, which would have told them in 5 minutes that it is broken, they looked for a code. How exasperating. The lesson for the consumer is, don't take "no code" for an answer. Insist that they try to replicate the problem. This of course is much easier to do if you yourself can replicate the problem at will. For intermittent issues, it's much more difficult to convince them to invest the time and effort to observe the problem.

 

[ILvolter]

Thanks for the information. Good suggestion about OnStar. First GM car in a while so I forget that option is there and what it is capable of doing.
We shall see what happens today with the car at the dealer but at least I now have greater confidence that something is wrong with the car. Can't fully blame them for the Saturday visit because by the time I got there the EV was at zero so I imagine it would be hard to diagnose the EV heater at that point. Made sure with use of Hold mode to give them the car last night with 30 left on the EV range.
Dealer kind of fell flat on their face after I took delivery. Car does not have 2nd key fob so they are ordering that as well as no owners manuals. Also they keep the charge cord separate and it was locked in parts department so I had to make a trip back the next day to get the cord. They gave me the car with an almost empty battery but a full tank of gas. So Monday was my first chance to really drive the car in EV mode. I love it and so does the wife so I really hope they get this fixed cause the loaner Cruze is one heck of a downgrade.

 

[Barry]

Hopefully you didn't clear the error message with an OBD11 scanner. I always try to leave specific instructions on how to duplicate the problem. And it has to be concise because a service writer will not type a paragraph. You get one sentence. And have them read it back, because they never seem to get it the first time. No matter what you say, they will just type "no heat." Get them to type something like "in electric mode, turn heat to high, blows cold air." That way, technician can't fail to find the problem unless he can't read 10 words.

 

[ILvolter]

Update.
Dealer called me this afternoon and said they are ordering parts. One person called it a control module and said it would be in on Thursday. Hopefully if all goes well they said I should have the car back Thursday afternoon. Sad they could not overnight the part but then again don't know how large this part is or where it is coming from.

 

[ILvolter]

Got the car back today! They replaced the heater control module last night. The dealer then charged it overnight and checked the heater today. Something in the notes about heater temp of 160 so I’m thinking that’s the electric heater temperature. Fingers crossed it’s fixed and I can start to enjoy my new car.

 

[jcanoe]

Got the car back today! They replaced the heater control module last night. The dealer then charged it overnight and checked the heater today. Something in the notes about heater temp of 160 so I’m thinking that’s the electric heater temperature. Fingers crossed it’s fixed and I can start to enjoy my new car.

160F is normally the temperature of the Volt's gas engine coolant that must be reached before the engine heat is used to provide heat for the passengers when using Hold Mode or Mountain Mode. Engine Assist Heat will briefly display the Engine Running Due to Temperature (ERDTT) message on the driver's information console. When ERDTT is active the engine coolant will reach ~150F then cycle between 120F and 140F.