2009 Nissan Pathfinder - Random temps hi

Why would my 09 Nissan Pathfinders ac blow hot then cold randomly. Also my heart was doing the same until I blead the lines. I let it idle yesterday to see if there was any kind of cycle of when the AC worked. The water started running out the over flow and when I drove it it ran hot. I let it cool filled back up with water and the heater is acting up again and also I can’t drive more than 5 miles without it reading hot. This is the crazy part. When hot temp shows the heat wont work then temp goes down and sounds like clicking under the dash while the clicking is happening the heat will work and temp is normal. Then it does all over again?

I blead the lines again after all the running hot and there was a huge air bubble pocket. So the heat is back right but haven’t checked the air yet. It was kinda cool yesterday so haven’t really had a chance to see if it will stay on. I will see today. No more running hot though. :star_struck: My main thing is to figure out what’s up with the air blowing cold then hot randomly?

Remove the radiator cap while engine is cold.

Start the engine, and as it idles watch the coolant in the radiator.

If bubbles start forming the coolant, there’s a blown head gasket.


This sounds like a head gasket leak. Combustion gasses are being pumped into the cooling system. Exhaust gasses displace some of the coolant. Some coolant and gasses get forced under pressure out the radiator cap into the expansion tank. The clicking is the sound of bursts of coolant rushing into the heater core.

Are you sure there is no external leak of coolant? If there is not and you have to add water/coolant, you are losing it out the exhaust pipe and the radiator overflow.

When it was getting hot it was blowing out the overflow. Even 5 mins after cranking. It hasn’t been doing it so thank goodness it was only air.

Burst of coolant into the heater core makes sense that’s what that was. Fingers crossed that the AC acts like it should but I don’t think it will. The AC acting up is what caused me to make it over heat to start with. I’ve read allot of post about the Pathfinders AC and a huge amount of owners had problems with them. It worked fine when I bought it but now I can get into it one day and it will work the whole time. Tomorrow it won’t work at all and next day it might work 20 min then stop. Cutting the car off then on again seemed to help but might have just seemed that way? I really don’t have the money for someone to charger me arm and leg just to diagnose the problem.

Most days it works 10 min then blow warm then kick back in for 10 min then blow warm.? It’s crazy?

Forget about your AC for a moment… You need to determine the cooling system problem first and foremost. It does indeed sound like you have a head gasket problem…this is of course after you verify that you do not have an external coolant leak somewhere. If you dont have a head gasket problem you will create one by repeatedly driving this using the AC while there are obvious air pockets in the cooling system you may be overheating this engine during these tests…it just doesn’t register as such because of the air pockets.

It is imperative you find and fix the cooling system issue and burp all the air from the system before doing anything else. Once you figure that out then you can play around with the AC.

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I knew what the over heating problem was. There was air in the lines. I got all the air out. No more over heating! The A C is what is really tripping me out.

I was driving the other day and I noticed when I slowed down that the compressor clicks back on at 40 mph exactly! If I take it easy it will stay on for a lil while even over 40. What could 40 mph have to do with the compressor clicking on? It was the head gasket! $1900 later it’s all better. :worried:

It is computer controlled… It engages and disengages as it sees fit due to load and several other factors.

You only need to worry about it if it isnt getting cold or operating inside the cabin properly. Aside from that dont worry about how it goes about its business…they dont stay on the entire time under normal conditions.

If you are low on refrigerant it will cycle on and off rapidly…say at 10 second intervals or so…when it does that…then you know you have a problem. But from what you describe it doesn’t seem like anything is wrong. Then again you havent described how it behaves inside the cabin as of late…or have you?

Well the problem was found and fixed. The thermostat was stuck open is why it was getting cold sometimes but not all times. When I fixed that it was obvious it was a blown head gasket. $1900 later it’s all better air conditioning and all!

Good to hear you got the cooling system problem solved and back on the road w/a reliable runner, AC doing its job and all. Good for you. Cooking grocery store steak and fish at home until the $1900 is paid off instead of dining at the local surf-and-turf restaurant, the only compromise. Except for the restaurant owner and staff, not a bad deal at all.

Luckily my husband makes good money! We paid in full and only had to borrow 500. That’s paid back and on to the next problem life throws. :wink: Proud to have something reliable after 6 years of bad vehicles. Thanks

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