Hi everyone, I’m the new kid. Actually, I have 14 years working on Nissan and 5 years with Infiniti... my wife tells me her 2001 Maxima is overheating while she’s on the interstate, at speed, with the air conditioning on... she turns the Ac off and sets the heat as high as it will go...immediately... and engine cools down. Now... I go check, guess what? Everything is normal... I don’t enjoy the convenience of a consult laptop anymore....so I can’t access memory.... both fans are operating and I see no fluid leaks. I’m on the way to remove the radiator and condenser to clean and straighten the fins on front. Does anyone have any other ideas?

Maybe the radiator hoses have gone soft and are collapsing when the water pump is driven quickly?
When cranking the heater up it allows the coolant to take another path? (possibly bypassing the possibly affected hose/s)

I'd wonder if there was a coolant bubble somewhere. Jack the front end up or park on a steep incline, start it, heat on full blast, and bleed the coolant system. You also may get more vehicle specific responses from the maxima forum.

Thanks for the suggestions guys! I didn’t find an air pocket and I checked for a head gasket leaking into the cooling system as well... No problem found. I spent an hour on the front of the condenser with a dentist pick, straightening cooling fins... after 250,000 miles, there was a considerable amount of restriction. I also checked the air conditioning pressures and found the low, suction side at 26 psi and the high pressure side above 250 psi.... and when revving the engine, low side drops down to 10psi indicating a restriction in the expansion valve. Also, possible air in the system with the high side almost pegged. I evacuated the system and flushed the expansion valve backwards, then vacuumed the system for 30 minutes. Recharged and now the pressures are 30psi low side and 225 high side... blowing very cold air inside the cabin. So far, my wife reports the problem is gone. I think I had a combination of issues...

I’ll tell on myself now. I’m ashamed... about 2 years ago, the compressor clutch idler locked up while my wife was on the way to work. My shop is only a couple miles away, so I grabbed a junkyard compressor for 26 bucks on the way to trade cars with her. I had a shop full of customer cars, so I replaced her compressor in the driveway and only evacuated the system for 5 minutes....blew some Freon in and got her car back to her before 5 o’clock. It’s been working now for almost 2years ... it’s true what they say... plumbers house has stopped up drains and mechanics drive clunkers... but my wife has a nice Maxima. Thinking about putting her in a newer car....any suggestions? I like the Q50 RED

Does anyone on here know an Infiniti corporate guy named Hisham Barbary?.. originally from Egypt... he was my instructor at Infiniti school in Pleasanton California.

Q50 is nice, but IMO a little pricey for what you get. Awesome that you figured the issue out though!

The Q50 can be quite a bargain if you purchase the right. They can be as cheap as a newer used Maxima, Camry, or Accord depending on which one you go with.

I would avoid the Red Sport, just because you are going to have a hard time finding one for less than $35,000 used. It's not really all it's cracked up to be either, unless you're really chasing horsepower. There are two better routes to go IMHO, that will get you an awesome one for a whole lot less money.

First and cheapest route - Get a 2014-2015 Q50, Non-Hybrid version. These came with the tried and true 3.7L V6 used in the 370Z and the Infiniti G37. It's a super reliable engine that makes right at 330hp and is easy. If you want something as reliable as the Maxima, i'd go this route, as they've worked out a lot of the bugs and the price tag on them have drastically. You're looking at somewhere around the $16,000-22,000 price range for one, depending on the year, type, and model you find. You get a lot of car for your money with that.

Second route - If you like the Red Sport, look at the 2016 and newer Q50's, but the non-Red Sport versions. Make sure they still have the V6, not the 4cyl. These models have the same exact engine as the Red Sport, just with smaller turbos and they make around 300hp vs 400hp. The secret to these are that they can be tuned to make just as much power as the Red Sport for very little money. You can pick them up in the lower the mid $20k range. The downsides to them are they suffer from the same bugs as the Red Sport, which they're still trying to sort out last I heard. They are also extremely cramped to work on. I'm sure they will improve, but if you like to work on your own vehicles, I personally wouldn't want to mess with having to maintain one. If you can get over those little issues though, it can be a pretty quick car for very little money.

Both of them have frustrating infotainment stereo systems on them, but the issues are more frustrating to others than they are to me. It can be a little laggy somethings and it is a little clunky for such a nice car. The car overall really feels like it should be a lot nicer than it actually is, but it's still a well optioned car for the money.

I drove Maxima's for years and they don't make Maxima's anymore that are nearly as well made as the one your wife currently has. Nissan doesn't even make anything in the same universe that is as good as the Maxima once was. The Q50 is a good car, but honestly even with what I said above I find myself regretting on a regular basis not just buying something else, instead of being loyal to the brand. They just don't make much worth buying anymore...

So, in summary - The Q50 is a decent car, but i'd spend my money on a Mazda 6 instead. MUCH, MUCH better car if you don't mind trading off some power. Fun to drive, great looking, super reliable, tons of options, and you can buy a new one for what a used Q50 costs.