My heat doesn't work on and speed

First of all your service light came on so give it a service then have the service light reset then check the thermastac, water levels and the choke is working properly and all the elecric working parts are good

Your vehicle speed sensor is mounted in the transaxle housing which is also subject to heating and cooling. The wiring harness to and from the speed sensor is also subjected to engine heating and cooling. Anybody that knows anything about electrical circuits can tell you that an electrical circuit's worst enemy is heat. You need to diagnose the vehicle speed sensor circuits like the code is TELLING you to do.

which fan are you talking about cooling Fan for Radiator or Blower Motor Fan for heat/AC

I have a 2000 pontiac grand prix with a digital climate control system. The heat quit working, it doesn't blow out any heat. Now that it is warm outside the air stopped blowing out any air. The digital temperature on the climate control is not correct. When it states that it is below 30 degrees on the ext and it is warm outside the air wont be cold. Once it starts going above 30 degrees the air gets colder. Today the blower stop working all together. Was told it maybe the climate control unit was bad. You can hear the door opening/shutting when you switch the temp from cold to hot. But there was no heat blowing out whatsoever in the winter time. Could you please give me your opinion on whether or not it is the climate control unit or something else?

Sounds like possibly a faulty ignition switch, They will cause symptoms very similar to that. Another thing 2001-2003s were known for are bad instrument panel clusters (dash assembly) usually the speedo gets pegged at a certain speed and stays there.

I just got the same problem on a 97 ford expedition, I have to start working on it, more likely would be a malconection issue or the swich unit check for any burned wires. and also check both the positive and the negative conection at the batrery. that all I'll keep you posted.

a 95 is only obd1 so problably wont get many codes. the oil is thicker in the first ten minutes or so, after it warms up the oil thins out. short of rebuilding the engine and/or doing a head job, try some lucas oil treatment or high tach. both are very viscous and help with thin oil

if its runnjing well for first few mins then chokes up i would suggest auto choke isnt turning its self off ,the cause of this is a miriad of things and to try changing bits ad hoc so to speak will cost more than what it would do to have it in the nissan garage.But dont be surprissed if you need a new ECU unit (computer) but lets just hope its a sensor fault

You have a vacuum leak that is not only affecting motor operation but also the correct operation of the vacuum switch controlling your damper. Need to have that matter resolved -check all vacuum hoses and fittings for integrity/tightness. Vacuum switch itself might be leaking!

check your water pump. when has it been replaced last? There is normally a 'tell-tell' hole behind the fan, on the pulley shaft housing. If its weeping water, you should replace it.

If your water pump is original, they are typically made of aluminum (newer cars) and from electrolosis, will deteriorate.