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New Bolt - No Heat

25K views 38 replies 14 participants last post by  capecodbolt 
#1 ·
OK, living in SoCal it took a few weeks to notice this but last night driving the Bolt home it was a little chilly and we couldn't get warm. I cranked the heater up to MAX temperature and not a bit of heat comes out. Thinking I was doing something wrong I re-read the manual, looked up posts here and tried every setting this morning but no heat. I'm assuming I need to bring back to the dealer to check out.

Before I go that route anyone have any easy checks? I looked at the fuses but honestly the only one I found that seemed to be related is called Aux Heat pump at 10 AMPs. The AC has worked fine on hot days; but I'd like this to work right as I have less than 500 miles on the car.

Is the heater electric or another system? I've read other threads complaining about too much heat; let's trade!!
 
#3 ·
Yes, I read the manual and tried everything including the Auto button on the knob.

If it is electric it makes me wonder if the connection to the heater is just loose. If anyone knows where it is located I would take a look and see if I can check the connection.
 
#4 · (Edited)
See page 253 of the manual. Then pop the hood. It is a electric, tankless hot water heater, just like we have in our back bathroom. But this one is 400 volts DC, not 120 volts AC. You had better hope the plug is not loose. :)

The heater is all the way back in the passenger side, against the firewall. It has an orange plug for the power, and heater hoses going into, and out of the right-hand side. Just to the right of the heater is its coolant reservoir. It should show pink coolant up to within an inch or so of the top. If you have the heater on high, the metal tankless heater should be almost too hot to touch. The hoses will be warm, as will the reservoir, If you put you hand on the reservoir, you should feel vibration from the 12 volt circulation pump, which is presumably what that fuse is for. The 12 volt coolant circulation pump is about a foot below the reservoir. You can just about see it with a flashlight, if you stick your head in there.
 
#6 · (Edited)
Thanks George, I went out and took a look and here is what I found which is even more confusing. Photo below to verify I am looking at the right components.

After looking over the connections which all seemed fine I cranked the heat to high in two modes, Auto and Manual.

Auto - pump is running, can feel fluid routing but the metal box gets colder to the touch as if AC running through it. Feels like car is blowing AC cold air.
Manual - no pump running, no fluid routing, metal box ambient. Feels like car is blowing ambient air.

Makes me think this is a control issue now.
 

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#9 ·
try max defrost and turn temp all the way up. Even in manual modes the heating / cooling system has a mind of its own. I sometimes just want fan on the windshield in the cold just to keep it from foggin up so I set heat and fan manually and turn off recirculate and heat & coll button and yet still with windshield selected the heater still runs :(
 
#10 ·
Good rule of thumb I found was when I wanted heat, I just set the target temp to 25F above outside air and made sure heating/cooling was on and the air directed to the center vents (not the feet or the defrosters). When in doubt, however, max out the target temp and if that still doesn't generate heat, sounds like a warranty issue.
 
#21 ·
Hey back alive and thawed out! Since I live in SoCal this heater issue has been of little concern during a summer that saw 115 degree temperatures and work has been so busy I didn't deal with. I decided to have it checked out when I did the software upgrade on 9/12/18.


Service Notes say:


Tech Cause: Heater control module does not communcate.
Ground Circuit .2 ohms to ground
Battery Voltage present at B+ terminal and test lamp illuminates
11.10 volts at LIN circuit
which leads to cooland heater control module replacement


It says they ordered the new control module but no word from them yet on arrival. I will call them tomorrow.
 
#25 · (Edited)
Just a note, 9/10 whenever you use defrost on any car (or when it decides to use it it'self) it will bypass your input (such as NO AC compressor or electric heater, or no recalculation) and use both AC and heat to defrost the window.

I think it is a safety related decision, as a fogged up windshield could be a safety concern, having to know how to operate the HVAC system to get the windows to defrost could mean trouble in court, because it's not common knowledge that both your A/C compressor and heater run to effectively remove fog as well as using outside air rather than recirculated air.

Crazy it needed a part, but crap happens, even new.
 
#26 ·
So the repair was completed in one day. Quite the difference and the heater now works great. I may have a chance to try it out tonight as we are heading out to the evening and it is supposed to be a little chilly this evening so I may actually have to use the heater on the way home!


The part was listed as 42597802 - Heater ASM-HTR COOL with a retail price of $825.13 but replaced for free under warranty. On the website GMParts.net this is the heavy duty heating unit that is on the left side of the engine bay towards the back when opening the hood. It never got hot but does now so my original unit must have been defective.



By the way has anyone used the GMParts.net site? It has great listings for the Bolt and may come in handy at some point.
 
#27 ·
Hey one other question; the heater fluid is a little low is this something you can buy somewhere or a dealer only supplied fluid? It's not that low and not worth returning to the dealer for a little fill up but it would be good to know where to get it one self.
 
#29 ·
The pressure caps, on the three coolant reservoirs, are a two piece, ratcheting assembly, like tamper-proof medicine bottle caps. I opened one by pushing down on the cap to create enough friction between the two pieces for it to unscrew. Fortunately, nothing broke. However, this is not the correct procedure. As explained by Professor John Kelly, of Weber Auto, the correct procedure is to rotate the outer cap until the slot at the cap edge aligns with the slot on the inner cap. Insert a screwdriver blade, or a key to hold the two pieces together while unscrewing. Re-installing the cap doesn't require any tools, as the ratchet inside the cap works in that direction.
 
#30 ·
Hiya. New Bolt owner (2019 bought in November). Having the same issues. Will check the fuses and fluid levels....

I live in NJ, and it's been below freezing this week, so getting this fixed would be nice..... [Not critical because the seat heaters are awesome, but still need the defrost + cabin heat on occasion.]
 
#31 ·
I'm near Princeton as well, perhaps you were my twin that I saw the other day (blue Premier)?

It's great to see more Bolts around here, there are already tons of Teslas; I see at least 5 - 8 on my daily 20-minute commute.
 
#35 ·
No heat - Burlington Ontario

Just entering my current data set.

I brought my (Mar 2018) Bolt back to the dealer on 19th of March 2019 and had the USB terminals worked on for non-function.
Also asked for a check on the heating system. I had several drop outs last summer, (blows like crazy inside dash - no flow or cool in cabin at any selected vent) and just had 3-4 no heat instances (blows like crazy inside dash - no flow or heat in cabin at any selected vent) in the days leading up to the USB terminal replacement.

It was in the shop for 20th and 21st. USB terminals are fixed. No fault found with the cabin heat system. No codes stored / found.

This morning (morning after bringing it home from dealer) 6:00am-7:00am there was no heat in the cabin - noticed ~25km into 50km trip.
I immediately took it back to dealer without turning vehicle off. Luckily - the S/A was able to yell loud enough over the blowing system to tell others also not to turn the vehicle off, since it was currently presenting the intermittent.

They did not find anything today. I sent in DOC ID:4695553 from Dr. Diesel showing TSB 17-NA-049, and DTC Codes B0173,B0178 to look for.

Will be without vehicle for the weekend. Will post an update when I have more data.
 
#36 ·
Was without vehicle on both Monday the 25th and Tuesday the 26th March, 2019. They were unable to "replicate" the no heat instance.
Unfortunately, someone might have turned it off that Friday morning that I brought it in - or it just thawed out as it sat in the work bay -maybe too busy too look at it.

I do have a lot more on this. Will post with useful outcome.
 
#37 ·
2018 Bolt - No Heat



Same No Heat occurred while parked at a Saturday 30th lunch a couple of doors down from dealer. Took it in immediately (again).
Got lucky and a Bolt mech. was there. Blowing like mad, no flow at outputs. Was raining out, and since I'd half-suspected a frozen evaporator, wanted to have it witnessed in operating environment - i.e.: minimize variables - cold 4°C rain outside and not thaw out in 21°C indoors. Mechanic agreed (can't say enough good things about this fellow).
Operated cam / output doors remotely with laptop. They appeared to behave - and in fact were. I agreed to move it inside, confident now that someone who knew what they were doing was on it. Removed glove box, cabin filter and snorkel - no signs of rodents (a good thing). Air was being forced back out through the input. Blockage? Inspection flex camera showed all doors operating as commanded by dash controls, but ice had built up on the evaporator and was completely blocking flow. Melted that down a bit with a heat gun through the intake, and normal heating resumed.

Next, evacuated and measured the mass of the refrigerant. It was 4.8% over charged from factory. (Don't have a tolerance available to me to say that +4.8% is good or bad.) Recharged to correct amount. Replaced cabin filter. Monitoring for the last week and one half, hoping the over charge was root cause - fortunately plenty of fog days. Unfortunately, problem still happens. Seems like when ambient is at 4.5g moisture per kg dry air or greater several (5+ instances) data points considered (Mixes of Temp. and RH%).

I suppose I was somewhat disingenuous when I said I would post again with something useful. Finding as suspect - the frozen evaporator - this was an A-HA! moment - but not solved yet.
The dealer has requested Engineering assistance from GM as to next steps. I'd like to get eyes on the drain tube myself while it is presenting - I can now visualize a manufacturing sticker lodged ~sideways in the drain port - not completely blocking drain... - but when I stopped in today - (hopeful for a quick hoist and a look)... I did not have an appointment. An appointment in this instance will mean that they rent me an Acadia/Cruze for a few days (and fuel out of my pocket each work order) while they wait for environmental conditions conducive to failure to try the next thing. i.e.: if it is cool and dry out (as it can be in the spring in Ontario) it will not ice up.

Anyhow... it has done this as early as 2 weeks in to ownership. I have had the Bolt for one year now - prior to my recent set of (3) work orders on it - I had made the error of assuming that "I" was not using it properly, or "it is an EV, - maybe this is how it operates?". Alternately - in the summer when there were several no cool instances, I'd "just deal with it" and switch to blow outside hot air over the evaporator to thaw it (I was only visualizing during those summer instances - but it turned out to be correct...) - then I could get A/C cooling again for a while - 32°C ambient at 80% RH, before it eventually just iced up again.

My posts are in the spirit of the original thread "New Bolt - No Heat" - and may or may not end up having the same root cause(s) as OP, but if it sounds familiar - then maybe it has already helped by triggering alarm bells while your warranty is still active. My fear is that the system is used to cool the battery, where cabin heat / cooling is just an interesting "side effect".
Maybe we shouldn't only look for codes thrown by the HVAC system (of which there were none for this failure while presenting), but in other systems.
 
#38 ·
Hopefully someone finds this useful. i.e. - if your A/C heat system blows like mad but nothing comes out the vents...

I have data to close my no heat issue which was part of this thread.

The fault was a low side pressure switch in the refrigerant system. This reported a continuous 19 P.S.I., (where measured actual was 84 P.S.I.,) causing the compressor to run continuously.

Removed and replaced under warranty. It has been two weeks with several instances of fog or rain where it should have frozen into a block and stopped working - but looks like it is corrected now.
 
#39 ·
The heating system in my 2017 Bolt was DOA when I acquired it in August 2017. The dealer had to employ some Bolt expert from outside of our area to come and replace the entire system. I believe what he did was "borrow" one from another Bolt they had on the lot.
It's been fine since.
My only issue is how much using the heat uses up the battery/ range of the car. Maybe a new design could remedy this in future models?
 
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