AC not blowing cold AND temperature gauge pegged to the top

[getserious]

My AC stopped blowing cold the other day, so I bought so A/C Pro and recharged it. On the first drive of a few miles everything was nice and cool, but on my next drive I felt the air slowly warm. At the same time, I looked down to find my temperature gauge in the danger zone. I know little about cars, so my question is, can these things be related? If so, what should I do? If not, I'm thinking I need to address the overheating issue first. Any advice would be appreciated.

Aside - my gas gauge started acting up a few months ago, so I guess it's also possible that my temperature gauge is just dying.

 

[JunkCrzr89]

Yes, they definitely can be related. Sounds like the AC compressor may have taken a dump, so engine is working harder, and you likely also have one or more cooling system problems that are contributing to overheating. How old is your radiator, fan clutch, water pump, and how many miles since last coolant change? Do not drive it until everything has been fixed, otherwise you may quickly end up with a blown engine.

 

[ramangain]

Get yourself a copy of Techstream to look at the sensor readings directly rather than relying on the gauge; especially since you said one of your gauges has already acted wonky.

If you kept the AC Pro bottle, what is your pressure reading when you reconnect it to the AC system now?

 

[riffman12]

the car will shut your A/C off if the engine temp gets too high (225 i believe)

so if the temp is pegged, you are beyond dangerously overheating the engine. If it's truly at the top I'd guess 240 plus?

fix that and your A/C may come back to life. just do not run the car if temp is getting that high

One failure point on these cars is the plastic heater T's at the back of the engine crack, and you lose a bunch of coolant, overheating the engine in a matter of minutes/seconds

 

[getserious]

Yes, they definitely can be related. Sounds like the AC compressor may have taken a dump, so engine is working harder, and you likely also have one or more cooling system problems that are contributing to overheating. How old is your radiator, fan clutch, water pump, and how many miles since last coolant change? Do not drive it until everything has been fixed, otherwise you may quickly end up with a blown engine.

I don't think I've done any of those things since I've owned the car, except the coolant change. Car has 180k miles and I bought it with 135k.

 

[getserious]

Get yourself a copy of Techstream to look at the sensor readings directly rather than relying on the gauge; especially since you said one of your gauges has already acted wonky.

If you kept the AC Pro bottle, what is your pressure reading when you reconnect it to the AC system now?

I hooked the A/C Pro back up and coolant is within the desired range.

 

[getserious]

the car will shut your A/C off if the engine temp gets too high (225 i believe)

so if the temp is pegged, you are beyond dangerously overheating the engine. If it's truly at the top I'd guess 240 plus?

fix that and your A/C may come back to life. just do not run the car if temp is getting that high

One failure point on these cars is the plastic heater T's at the back of the engine crack, and you lose a bunch of coolant, overheating the engine in a matter of minutes/seconds

If I hear you correctly, you're saying I should get towed to the shop? It's about five miles away.

I did replace the heater T's about 1,000 miles ago, so I don't think that's it.

 

[Ayune]

When the engine is cold, check the coolant level in your radiator and report back. Not the level in the white overflow bottle, but the actual radiator.

 

[nissanh]

Do exactly what ^^^ said.
If the radiator is clogged internally, this can happen as well.
A faulty fan clutch, clogged radiator/AC condenser fins can also contribute to overheat.

 

[riffman12]

If I hear you correctly, you're saying I should get towed to the shop? It's about five miles away.

I did replace the heater T's about 1,000 miles ago, so I don't think that's it.

If the temp gauge is truly pegged at the top I would not run the engine at all, let alone drive it 5 miles.

 

[ramangain]

When you changed your heater Ts, did some of the plastic break off and become unrecoverable from inside the hose(s)?

 

[getserious]

When the engine is cold, check the coolant level in your radiator and report back. Not the level in the white overflow bottle, but the actual radiator.

I checked in the radiator Fluid appears clean and about 2-2.5 inches below the cap. Not sure what is normal, but it seems normal. I did look at the reservoir as well. Hard to tell, but that level appears to be BELOW the lowest line.

 

[getserious]

When you changed your heater Ts, did some of the plastic break off and become unrecoverable from inside the hose(s)?

I had my mechanic do it.

 

[KFunk740]

I don't think thats dangerously low coolant, but definitely lower than it should be, especially for one that someone recently messed with, at which point he should've topped it off and bled the air bubbles out. It should be up closer to the high line on the expansion tank, and near the top on the radiator itself.
My bet is on a slow coolant leak (mechanic didn't get hose clamps on perfect when he did heater Ts?), leading to an air bubble in the system that found its way to the temp sender (which would peg temp gauge).

 

[getserious]

I don't think thats dangerously low coolant, but definitely lower than it should be, especially for one that someone recently messed with, at which point he should've topped it off and bled the air bubbles out. It should be up closer to the high line on the expansion tank, and near the top on the radiator itself.
My bet is on a slow coolant leak (mechanic didn't get hose clamps on perfect when he did heater Ts?), leading to an air bubble in the system that found its way to the temp sender (which would peg temp gauge).

I think I owe an apology for using the word "pegged" incorrectly. During my last drive, it was at the very top and not moving, so I said "pegged." I've since cranked it twice to move it out of the garage and check AC levels and both time the temp gauge was normal. So it's not permanently "pegged."

 

[JunkCrzr89]

I checked in the radiator Fluid appears clean and about 2-2.5 inches below the cap. Not sure what is normal, but it seems normal. I did look at the reservoir as well. Hard to tell, but that level appears to be BELOW the lowest line.

View attachment 2395323

View attachment 2395324

View attachment 2395335

Clearly your problem is not coolant and unlikely a blown head gasket. Something is either restricting the flow of coolant in the system (thermostat or water pump) causing it to overheat, or your ECT sensor and/or dash gauge is faulty causing false readings.

If you turn your ignition to the ON position but do NOT start the engine, what does the temp gauge do?

 

[JunkCrzr89]

I think I owe an apology for using the word "pegged" incorrectly. During my last drive, it was at the very top and not moving, so I said "pegged." I've since cranked it twice to move it out of the garage and check AC levels and both time the temp gauge was normal. So it's not permanently "pegged."

Then the dash gauge and ECT sensor are working properly. My bet is still on thermostat or water pump being your problem.

 

[ramangain]

Do you think your gauge may have just gone wonky, like the other one did?

 

[getserious]

Clearly your problem is not coolant and unlikely a blown head gasket. Something is either restricting the flow of coolant in the system (thermostat or water pump) causing it to overheat, or your ECT sensor and/or dash gauge is faulty causing false readings.

If you turn your ignition to the ON position but do NOT start the engine, what does the temp gauge do?

The needle doesn't move. It's all the way at the bottom.

 

[ramangain]

You
Need
Techstream