HVAC (A/C) cuts out

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Marktm

Well-known member
Leaf Supporting Member
Joined
Jan 21, 2016
Messages
854
Location
Houston, TX
Stored DTCs - B2785 B2786 B2791 HVAC. A/C cuts out for several minutes. This has happened a number of times - usually for 2-5 minutes, then A/C slowly cools down again. This happened yesterday on the freeway. Outside temps were almost 100 oF - got a little uncomfortable before cooling started again.

Any such experience/remedies?
 
Marktm said:
Stored DTCs - B2785 B2786 B2791 HVAC. A/C cuts out for several minutes. This has happened a number of times - usually for 2-5 minutes, then A/C slowly cools down again. This happened yesterday on the freeway. Outside temps were almost 100 oF - got a little uncomfortable before cooling started again.

Any such experience/remedies?

The first two codes are for over-heat with possible causes being the compressor itself, cooling fan, or low refrigerant and/or leak

Oddly enough the third code is for "low speed high load" which has one of the possible causes as "refrigerant overfill". But perhaps that's happening upon restart.

If this happened on the freeway at cruise speed, I'd think that'd rule out the cooling fan. If it was stop-and go the cooling fan would be a suspect. I'd definitely check the refrigerant pressure. Does your AC seem a bit weak even when it's running?
 
First - appreciate the good comments:

- When this happened we actually were slowing and near stopping on the freeway
- Similar situation as best I recall was while quite hot (not 95+, but hot) and in stop and go traffic
- I've never had the A/C checked for proper refrigerant load, and it is factory original charge (no records of any maintenance required when I bought the car)
- There is some noise (minor) from the equipment hood that appears to be coming from the compressor (with HVAC on). Both fans run and appear to be quiet and unrestricted.
- Possible that this is a common problem with extremely hot weather (design issue)? I watch the climate control power screen and know that when this happens, the kW drops to zero. What is strange is that the power level (on A/C only) will often climb to over 2 kW - almost like the
heater circuit is on even though the set temperature is well below ambient and cabin temps. I guess I need to make the mods to cut the
heater circuit out completely during hot months.
- The A/C does a great job of quickly cooling the car with plenty of cold air.
- bottom line? have the refrigerant level checked??
 
The HVAC controller will turn off the compressor if evaporator temperature gets close to freezing (32 F or 0 C) so check to make sure cabin air filter is not restricting air flow and run blower fan at moderate to high speeds for maximum cooling. Your description of cooling loss for 3-5 minutes is consistent with evaporator freeze protection. Condenser fans should move a lot of air and make some noise so check air flow since the error codes indicate overheating and the controller will shutdown the compressor to protect it (this would also yield the symptoms you have). I installed a temporary resistor to keep the heater from turning on in my 2011 and could still see at least 3 kW compressor draw under high ambient conditions so your 2 kW load is reasonable. The heater on while using A/C happens at moderate temperatures so it probably was not involved in your loss of cooling condition (although I highly recommend the modification and would have purchased the plug-and-play kit if my 2011 had not been totaled).

The A/C systems in both 2011 and 2015 work great in high ambient temperatures so your symptoms are not normal.
 
GerryAZ said:
The HVAC controller will turn off the compressor if evaporator temperature gets close to freezing (32 F or 0 C) so check to make sure cabin air filter is not restricting air flow and run blower fan at moderate to high speeds for maximum cooling. Your description of cooling loss for 3-5 minutes is consistent with evaporator freeze protection. Condenser fans should move a lot of air and make some noise so check air flow since the error codes indicate overheating and the controller will shutdown the compressor to protect it (this would also yield the symptoms you have). I installed a temporary resistor to keep the heater from turning on in my 2011 and could still see at least 3 kW compressor draw under high ambient conditions so your 2 kW load is reasonable. The heater on while using A/C happens at moderate temperatures so it probably was not involved in your loss of cooling condition (although I highly recommend the modification and would have purchased the plug-and-play kit if my 2011 had not been totaled).

The A/C systems in both 2011 and 2015 work great in high ambient temperatures so your symptoms are not normal.

Ordered a new filter - appears easy to replace
Both fans operate quietly and pull lots of air
The compressor is little noisy, in fact I thought it was the inverter humming until checking more closely (due to this issue)
Good to know that the A/C unit itself will pull up to 3 kW. Don't know that I've seen that high, but when on full blow/cool, it still cools the cabin down quickly
Going to finally order the kit - just makes sense in Houston as the heated seats/steering wheel work 99% of the time

Thanks for the info.
 
I have a 2011 leaf and just started playing with LeafSpy in the last 30 days. I have the same 3 codes - B2785, B2786, and B2791. I've been debating what to do about it, since the car still cools itself well. I've noticed it cut off from time to time, but nothing that would be alarming or cause me to take it to a shop. I already cleared the codes 5 days ago and changed the filter. The codes re-appeared, so I have to assume the filter was not the problem. My next thought is to check the refrigerant level. If anyone has a link to a refrigerant checking tutorial, please link it :). I hate to go pay nissan to diagnose this when it's not a "real" problem yet. IE wife isn't complaining yet.
 
The 2012 manuals are available free on-line. The two that are needed for HVAC diagnostics/repair are:
HA.pdf
HAC.pdf
It's likely they will work for your 2011 also and have very complete documentation.
 
GerryAZ said:
The A/C systems in both 2011 and 2015 work great in high ambient temperatures so your symptoms are not normal.
Ditto for 2012! My black SL chills down very quickly in the hot sun. You should experience the same indeed.
 
Marktm said:
Ordered a new filter - appears easy to replace
...

Thanks for the info.

I haven't changed mine, but many here have reported the approved way of replacing the cabin filter is very difficult. Much easier to remove the glove box entirely to get at the filter.
 
dsh said:
I have submitted Case # 35668713 to EV Customer Service re: 2011- Current LEAF's A/C Blowing Warm Air Intermittently. if anybody experiences or has the same issues, please add your complaints to the Case # above... maybe Nissan will finally get this corrected and/or offer a software update, as it appears a previous software update caused the problem in the first place.

Why do you make me see this three times?
 
stjohnh said:
Marktm said:
Ordered a new filter - appears easy to replace
...

Thanks for the info.

I haven't changed mine, but many here have reported the approved way of replacing the cabin filter is very difficult. Much easier to remove the glove box entirely to get at the filter.

I did replace the air filter end of last summer - it was fairly easy, in fact if I remember, closing the cover was the most difficult, but it's been over a week ago :roll: !! I did not have any more issues with the A/C cutting out, but the hottest part of the TX summer is coming, so I'll see how it goes.
 
My AC cut out after sitting still 3 hours in 95F heat in the sun. I was using my car as an office at the time. Power draw was 3-4kW, then went to 0 suddenly. I drove the car for 1 mile at 35mph and it suddenly came back strong, only drawing 1-1.5kW.

I was told on the forums there was a firmware update for the AC that cut the cooling power for early 2011s under certain conditions. But it's only happened when stationary once so I've never done anything about it.

If you we're driving at all when this happened, I suspect something is wrong with the car. I would replace the cabin air filter, and if it continued, check freon levels and whether the outside coil is obstructed.
 
Lothsahn said:
My AC cut out after sitting still 3 hours in 95F heat in the sun. I was using my car as an office at the time. Power draw was 3-4kW, then went to 0 suddenly. I drove the car for 1 mile at 35mph and it suddenly came back strong, only drawing 1-1.5kW.

I was told on the forums there was a firmware update for the AC that cut the cooling power for early 2011s under certain conditions. But it's only happened when stationary once so I've never done anything about it.

If you we're driving at all when this happened, I suspect something is wrong with the car. I would replace the cabin air filter, and if it continued, check freon levels and whether the outside coil is obstructed.

This is exactly the problem we're having...doesn't just happen while stationary it also happens while driving. It has nothing to do with the air filter or the freon levels or the condenser fin coils. I notice it more cuz I'm in Phoenix and it gets regularly up 115 degrees in the summer....

Anybody with the new 62 kWh Leaf Plus have the same intermittent A/C blowing warm issue?
 
dsh said:
Lothsahn said:
My AC cut out after sitting still 3 hours in 95F heat in the sun. I was using my car as an office at the time. Power draw was 3-4kW, then went to 0 suddenly. I drove the car for 1 mile at 35mph and it suddenly came back strong, only drawing 1-1.5kW.

I was told on the forums there was a firmware update for the AC that cut the cooling power for early 2011s under certain conditions. But it's only happened when stationary once so I've never done anything about it.

If you we're driving at all when this happened, I suspect something is wrong with the car. I would replace the cabin air filter, and if it continued, check freon levels and whether the outside coil is obstructed.

This is exactly the problem we're having...doesn't just happen while stationary it also happens while driving. It has nothing to do with the air filter or the freon levels or the condenser fin coils. I notice it more cuz I'm in Phoenix and it gets regularly up 115 degrees in the summer....

Anybody with the new 62 kWh Leaf Plus have the same intermittent A/C blowing warm issue?

As I understand it, dsh, you should not be experiencing this issue. If you have a 2011 or possibly a 2012, I'd call a knowledgeable dealership and see if there are any TSB's about the AC cutting out. Since we don't have 115F here, and I don't plan on running the AC without moving the car for >3 hours, I haven't bothered to fix it on mine.
 
This is probably on purpose. Most vehicles will cut off things that are being used in the accessory mode after a while to preserve the 12v battery from dying. OR the heat pump may not have have reached a limit for use when the car is stationary.

Run the for a bit and then it will reset its timer.
 
OrientExpress said:
This is probably on purpose. Most vehicles will cut off things that are being used in the accessory mode after a while to preserve the 12v battery from dying. OR the heat pump may not have have reached a limit for use when the car is stationary.

Run the for a bit and then it will reset its timer.

<sigh> First, the A/C doesn't run in Accessory mode - it's a high voltage unit that requires Ready Mode. Second, you left a rather necessary word (car?) out of your suggestion and one of the sentences doesn't make sense as written. I wish that people posting from cell phones would check the post before sending it, especially when offering advice.
 
dsh said:
Lothsahn said:
My AC cut out after sitting still 3 hours in 95F heat in the sun. I was using my car as an office at the time. Power draw was 3-4kW, then went to 0 suddenly. I drove the car for 1 mile at 35mph and it suddenly came back strong, only drawing 1-1.5kW.

I was told on the forums there was a firmware update for the AC that cut the cooling power for early 2011s under certain conditions. But it's only happened when stationary once so I've never done anything about it.

If you we're driving at all when this happened, I suspect something is wrong with the car. I would replace the cabin air filter, and if it continued, check freon levels and whether the outside coil is obstructed.

This is exactly the problem we're having...doesn't just happen while stationary it also happens while driving. It has nothing to do with the air filter or the freon levels or the condenser fin coils. I notice it more cuz I'm in Phoenix and it gets regularly up 115 degrees in the summer....

Anybody with the new 62 kWh Leaf Plus have the same intermittent A/C blowing warm issue?

My 2011 did and my 2015 does work very well as a portable office in Phoenix. Although the compressor will not run at full speed while parked, it still provides very good cooling even on the hottest days. There was a software update for 2011 models that did several things, one of which was to reduce the maximum allowable compressor speed when the car was parked or moving less than 18 mi/hr (threshold for pedestrian warning noise). Based upon my observations of the 2015, that programming was carried forward because compressor power draw increases and discharge air temperature decreases when vehicle speed gets above 18 mi/hr during really high ambient temperatures (it is not noticable at moderate temperatures). I have never seen the over temperature error codes nor had the air conditioning cut out as described in several posts in this thread (with either 2011 or 2015) so there is something wrong with those cars. Possible causes include condenser fans not moving enough air (due to condenser blockage or fans running too slow), evaporator icing (due to low circulating fan speed or restricted cabin air filter), or incorrect refrigerant charge (not likely because system is hermetically sealed). I have seen the same symptoms with gasoline engine vehicles when the electric condenser fan was not operating at all, variable speed controller for the condenser fan was not running the fan fast enough, and/or the thermostatic fan clutch for the engine-driven fan was not working correctly (also caused coolant temperature to climb). I have also seen failing electric condenser fans just run slower than normal and not move enough air even though they sound like they are working.
 
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