The heat and air conditioning on my 2.5 l 2003 Nissan Altima keeps cutting in and out?

The problem is not with the fan - that runs steady at whatever speed I select. I took it to my local garage and they couldn't fix and and they brought it to radiator shop and they couldn't fix it. I get heat/ac once I get onto the highway after some of driving, but it will come and go on a regular basis and I get what seems to be just outside air. It seems that it will cut out consistently when I come off the highway and so my wife thought it had something to do with changing gears and I thought there may be a connection to RPM's. This may be the case, but it will also cut out when I keep the RPM's constant. I put coolant in the overflow tank and it seemed to take quite a bit and is now holding steady and I still have the problem. I could add coolant to the rad, but not sure how high it should be. Should I see coolant when I take the cap off? Don't want to bring it to the dealer because I don't trust them.The heat and air conditioning on my 2.5 l 2003 Nissan Altima keeps cutting in and out?
Yes for one you should see coolant when you take the radiator cap off. Second your thermostat could very well be stuck open. If that's the case then your coolant is constantly flowing throughout your engine block and it's not getting quite hot enough for your heater to blow out hot air. The heater core in case you didn't already know is located in your firewall and has two hoses connected to your intake(engine) and radiator. The heater core is what the coolant travels through with the fan located nearby and that is how you get heat for through your vents inside. Lastly it could be your climate control knob/button. There is a flap that within your dash usually underneath that controls wheather or not your getting the heat(hot air)from your heater core or cold air from your air conditioner. If the flap is stuck or the motor on it is inoprable then that is your problem. I know dealerships cost out the %26quot;ying yang%26quot; but sometimes that is the best/safest way to go rather than take it to a shadetree mechanic. I tried to explain it too you the best I could. It's alot easier to understand if I were to show you on your vehicle in person. Anyway hope this shed a little light on the subject for you. Good luck....The heat and air conditioning on my 2.5 l 2003 Nissan Altima keeps cutting in and out?
id start with the cooling system. if you had to add coolant, then there is a leak somewhere. that system is sealed and usually does not require top offs. just flushes from time to time.



the other option is that the cooling fans are not working under the hood. it sit directly behind the ac condenser and radiator. if the coolant is low, usually the coolant temp sensor reports the temp inaccurately, which would not allow the computer to register the proper temp at the cars computer (which actually control the radiator/ac condenser fan.The heat and air conditioning on my 2.5 l 2003 Nissan Altima keeps cutting in and out?
Take to a auto air-condition service unit. the trouble may be with

1. air conditioner's thermostat/sensor

2. Leak in the A/C refrigerant

3. Slackened A/C drive belt.The heat and air conditioning on my 2.5 l 2003 Nissan Altima keeps cutting in and out?
Similar problem with my Dodge Dakota truck, everything would cut off on acceleration or when pulling on a hill...caused by a vacuum leak...when vacuum was insufficient, the system would %26quot;default%26quot; and all the little doors under the dash would close...just something to think about...K ;o)