Preheating works but when driving heating is COLD (??)

My Nissan Leaf Forum

Help Support My Nissan Leaf Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

markpalmos

Member
Joined
Jul 26, 2020
Messages
16
Hi all,
For some reason I don't understand, my car warms up when I set it to heat up 15 mins before I leave the house to drive... but when I am driving it blows cold air only. The seat and steering wheel heat work.

Do you know what this might be ? (PS - I'm not very savvy on the tech terms with this car, so please explain rather than just say "the flambideoopsdinks is not hypercharging anymore..." :D )

Thanks,
Mark.
 
markpalmos said:
Hi all,
For some reason I don't understand, my car warms up when I set it to heat up 15 mins before I leave the house to drive... but when I am driving it blows cold air only. The seat and steering wheel heat work.

Do you know what this might be ? (PS - I'm not very savvy on the tech terms with this car, so please explain rather than just say "the flambideoopsdinks is not hypercharging anymore..." :D )

Thanks,
Mark.

TLDR: Turn on the AC. Report on what happens.

To preheat, resistance heat is used. While driving in moderate temperatures, the heat pump/AC heats unless the AC is on, and then resistance heat is used as the heat pump/AC is being used for cooling. So if the heat pump isn't working, you can get heat by turning on the AC. Which will not do any cooling, as I suspect that the heat pump/AC isn't working.
 
I would suspect the opposite. The electric PTC is *not* working and the heat pump is doing all the work. Not sure which year or model the OP has though, since that was more of a Gen 1 setup that had this issue.

[edit] it was a 2015, so I suspect the PTC then.
 
knightmb said:
I would suspect the opposite. The electric PTC is *not* working and the heat pump is doing all the work. Not sure which year or model the OP has though, since that was more of a Gen 1 setup that had this issue.

[edit] it was a 2015, so I suspect the PTC then.

One of the two isn't working. Toggling the AC button will diagnose it. If it works (provides heat in moderate temperatures) with the AC off, then you are correct. if it works with the AC on, my guess is correct.

I think I've heard about more PTC failures than heat pumps. So your bet is a better one.

The preheat, as I recall, uses both PTC (to heat) and AC (to defog), and OP reported that worked. Is this correct?
 
WetEV said:
The preheat, as I recall, uses both PTC (to heat) and AC (to defog), and OP reported that worked. Is this correct?
Correct.
Would be unusual for a heat pump failure and not a PTC failure...but neither are exactly good. Would be good for the OP to report back if that is in fact the case.
 
markpalmos said:
Hi guys, thank you very much for the input. But what is a PTC? Is it expensive to repair?
Tx
Mark
Very.
The "PTC"--also referred to as a "resistance" heater--was originally the only heating element on early Leafs (like mine). It was also the source of what I call "infant mortality" failures (e.g. cars with heaters that were nearly DOA).
At any rate, it sounds like your problem is the heat pump (also not a cheap repair)...which was added in later model years to increase efficiency/range (PTC heaters draw a lot of power).
 
The only reason I suspect the PTC heater is because I have a 2015 Leaf SV at my house (family member, not mine) and doing the pre-heat uses the heat pump (and PTC) at the same time while charging or connected to the L2 on my house. If the temperature is really cold, then the heat-pump will struggle without the PTC to give it some backup heating. The PTC can heat the entire car without the heat-pump assisting, but it doesn't work that well the other way around if the temperatures are very cold and wet outside.
 
Stanton said:

Yikes...

knightmb said:
The only reason I suspect the PTC heater is because I have a 2015 Leaf SV at my house (family member, not mine) and doing the pre-heat uses the heat pump (and PTC) at the same time while charging or connected to the L2 on my house. If the temperature is really cold, then the heat-pump will struggle without the PTC to give it some backup heating. The PTC can heat the entire car without the heat-pump assisting, but it doesn't work that well the other way around if the temperatures are very cold and wet outside.

Ok thanks... I may have to get an extra sweater and gloves instead!
 
markpalmos said:
I may have to get an extra sweater and gloves instead!

If it is the heat pump, you can likely get heat by (odd as it sounds) turning on the AC. 30 C days might be a bit of a challenge, as might damp days with condensation.

If it is the resistance heat aka PTC, you can get heat from the heat pump by turning off the AC. Will not work well on cold days, below 0 C. But will work to an extent colder than that.
 
WetEV said:
If it is the heat pump, you can likely get heat by (odd as it sounds) turning on the AC. 30 C days might be a bit of a challenge, as might damp days with condensation.

If it is the resistance heat aka PTC, you can get heat from the heat pump by turning off the AC. Will not work well on cold days, below 0 C. But will work to an extent colder than that.

Interesting... from that it seems it's not the PTC Or Heat Pump as temps have not reached freezing yet, and the heat has not worked at all with the AC off. I will try again with AC on, though I have already done that inadvertently by pressing the demist button where AC comes on with the "heating", and the air is very cold, no warming at all... The only scenario where there is heat is when I'm charging and set the car to preheat. Dang, disappointing it's going to be very expensive regardless...
 
markpalmos said:
Interesting... from that it seems it's not the PTC Or Heat Pump as temps have not reached freezing yet, and the heat has not worked at all with the AC off. I will try again with AC on, though I have already done that inadvertently by pressing the demist button where AC comes on with the "heating", and the air is very cold, no warming at all... The only scenario where there is heat is when I'm charging and set the car to preheat. Dang, disappointing it's going to be very expensive regardless...

A quick and easy test. Plug it in to get it charging, set your preheat to go off in the next few minutes. Open the hood and listen for the heat pump to come on, you can't miss it. If instead, all you hear is the cabin fan come on and it's quiet, but you feel heat coming out of the vents, it's probably your heat pump that is out. But... if you do hear the heat pump and you can feel warm air coming out from the vents, go ahead and turn the car on while charging, still plugged in, so all the dash lights come on, turn the heat on and set for 90F (32 C). Check if you feel the vents start to put out really hot air. That would mean you are getting the combo heat-pump + PTC both are working together. Otherwise, one or the other has failed, that should help you figure out which one is causing the issue.
 
knightmb said:
A quick and easy test. Plug it in to get it charging, set your preheat to go off in the next few minutes. Open the hood and listen for the heat pump to come on, you can't miss it. If instead, all you hear is the cabin fan come on and it's quiet, but you feel heat coming out of the vents, it's probably your heat pump that is out.

turn the heat on and set for 90F (32 C). Check if you feel the vents start to put out really hot air.

Hi @knightmb
I did the test and could not hear anything substantial up front, fan was on, blowing warm.
Then later on, I tried with the heat full blast and AC ON... and what do you know, warm, air while driving! That's bloody weird, but as an emergency measure, works... I only tried it once, so am not sure if it will work as the temp outside drops below freezing.

So do you reckon this is a Heat Pump then?
Thanks so much for your help.
Mark.
 
markpalmos said:
Then later on, I tried with the heat full blast and AC ON... and what do you know, warm, air while driving! That's bloody weird, but as an emergency measure, works... I only tried it once, so am not sure if it will work as the temp outside drops below freezing.

Sounds like failed heat pump and working resistance heat. If so, should continue to work at cold temperatures.

Repairing the AC would allow for more efficient heat, clearing the windows on warmer wet days and cooling in the summer. Cost would vary, depending on what is wrong the the AC.

Depends on what you want and need.
 
markpalmos said:
Hi @knightmb
I did the test and could not hear anything substantial up front, fan was on, blowing warm.
Then later on, I tried with the heat full blast and AC ON... and what do you know, warm, air while driving! That's bloody weird, but as an emergency measure, works... I only tried it once, so am not sure if it will work as the temp outside drops below freezing.

So do you reckon this is a Heat Pump then?
Thanks so much for your help.
Mark.

Yeah, sounds like. The two work together, and the PTC heater is the "backup" when the Heat Pump can't produce enough heat. But since the Heat Pump is not working at all, the Leaf thinks everything is fine and never uses the PTC heater. But as was suggested by others, turning on the AC and Heat at the same time, forces the PTC heater to be used since the Heat Pump can't do both cold and hot air simultaneously.

So that means you won't have AC during the summer months and you'll take a bigger range hit using heat during the winter months, but you won't freeze at least. It's possible that it's a Freon issue with the heat-pump, maybe it all leaked out? But you can't put regular store bought Freon in it, it takes a special kind. Anyone here that knows more about the Gen 1 heat-pumps might be able to help troubleshoot that part.
 
knightmb said:
Yeah, sounds like. The two work together, and the PTC heater is the "backup" when the Heat Pump can't produce enough heat. But since the Heat Pump is not working at all, the Leaf thinks everything is fine and never uses the PTC heater. But as was suggested by others, turning on the AC and Heat at the same time, forces the PTC heater to be used since the Heat Pump can't do both cold and hot air simultaneously.

So that means you won't have AC during the summer months and you'll take a bigger range hit using heat during the winter months, but you won't freeze at least. It's possible that it's a Freon issue with the heat-pump, maybe it all leaked out? But you can't put regular store bought Freon in it, it takes a special kind. Anyone here that knows more about the Gen 1 heat-pumps might be able to help troubleshoot that part.


Thanks fella, yeah, actually, come to think of it... I do recall wondering why the aircon was so bad on a particularly warm day when I used the AC (generally I don't use it, just open a window!) - so that seems to confirm that it's the Heat Pump then?
 
markpalmos said:
Thanks fella, yeah, actually, come to think of it... I do recall wondering why the aircon was so bad on a particularly warm day when I used the AC (generally I don't use it, just open a window!) - so that seems to confirm that it's the Heat Pump then?
More than likely. You might have a silver lining to this though, you mentioned it was not working that well, but was any cool air coming out? It's possible that all the Freon leaked out and that repairing the leak and then re-filling it might fix the issue without having to replace the entire system.
 
knightmb said:
More than likely. You might have a silver lining to this though, you mentioned it was not working that well, but was any cool air coming out? It's possible that all the Freon leaked out and that repairing the leak and then re-filling it might fix the issue without having to replace the entire system.


Hell, that'd be good... I am taking it in next week to have them look at another issue (foot brakes not releasing properly when reversing each morning after parking on a sloped drive) and they say they'll look at the heating issue too... I will mention the possibility of the Freon being an easier cheaper fix!

Thanks again folks, very informative and useful thread.
I'll report back on what's done/found :)
Mark.
 
I know this thread is old, don't know if there is a newer one. but it is the one I found when my wife called last Thursday to say the heat wasn't working. Preheat works fine, no heat when she headed home from work (35 miles and high 20's °F). Found the "turn on A/C" suggestion but it doesn't do any good other than blow cool outside air with the temp set to 70°F.

Took it to Nissan Monday (happened to have an appointment for tire rotation and recall) and they determined the compressor is bad. I assume they mean the compressor for the heat pump. Should get the part today, install tomorrow morning. 30 mile drive but fortunately it will be above freezing and possibly a bit sunny.

Quote is $2,200!! But we bought, for the first time ever, the extended warranty which should cover most of the cost. Car was new Aug 2020, has 77K miles now because wife drives minimum 70 miles 7 days a week.
 
Back
Top