Recently I did a mayor repair on my 90SE VG Maxima, replace the engine because of bent valves and well mechanic didn't do a good job now is up to me to find some problems I currently have.

I do not have any heat at all, fresh air vent lever is closed, air circulation is on and still blows cold air with the fan on any speed. I remember (before the repairs) even with the fan being off I still feel some air coming through the vents but not anymore.

I have been checking my fluids and I noticed I'm loosing very little coolant over the days, I would say about 4 oz a week I need to keep refilling and I didn't have this problem before, today I checked again and found the reserve tank filled to the top and some coolant came out through the breather hole and a little spill on that area.

What could cause the cooland to go to the reserve tank and even spill it through that area?

Is this related to the problem with having no heat?

I don't have too much knowledge on this so I don't know where to start, I have searched and read about some cases being the thermostat but my temp needle is working ok, I was thinking maybe the stupid mechanic bypass the heater core but don't know how to check where the hoses go or how is supposed to be connected.

Thanks for your help.

 

If you're losing coolant, you've got air pockets which will result in cold air. Heater core I/O is at the firewall. It would be obvious if it were bypassed. Fill and bleed the system, check for heat, check for leaks.

 

^^^ What he said.

Sometimes you have to raise the front end of the car to bleed the air out, so park the car on an incline, the steeper the better. Make sure that the heater temperature lever is all the way to hot so coolant will flow through the heater core.

Read this TSB. It is extreme but sometimes it is needed:

http://maxima.theowensfamily.com/tsb/NTB90-079.pdf

 

Get a compression, and/or leakdown test done.
I see this symptom, I think two things: blown headgasket, or overheating motor.