# Ac problems on '88 300zx



## RackZX (Sep 3, 2005)

Hi, Sorry if this is beating a dead horse to death, but I did a search and found different post on other model Nissans but nothing on the 88 300zx. I had my system drained by a mechanic and bought some of the refrigerant from Advance Auto and followed the instructions. The ac blew cold for about 2 minutes then started blowing heat out the defroster ports and the floor vents. Even with the ac/defrost off it blows heat out constantly. My wifes uncle who I bought the car from said he could get it to blow cold every now and then. I did not know if I would have to replace the vaccuum motors, compressor or everything. If anyone could help it would be much appreciated.


Billy


----------



## Zen31ZR (Mar 24, 2004)

The climate control system in those cars is a major pain to deal with. First of all, make sure you don't have any vacuum leaks. The floor and defrost are the default setting, that's where it will go if there is no vacuum. If there is no vacuum it will also default to the heat setting. Sounds like you've got to do some vacuum line tracing, probably some replacement. Makes sure the system still has refrigerant in it. The weakest point on all A/C systems is the pulley seal in the nose of the compressor.


----------



## AZ-ZBum (Nov 21, 2004)

actually, you start in the engine bay. most of the vacuum issues originate there.


----------



## RackZX (Sep 3, 2005)

Thanks Guys, I hope it is just a vacuum line or two. I read somewhere that a guy had to pull his dash out to replace 2 vacuum motors and once completed his air worked fine. It seemed like alot of work to replace them. I will post as soon as I can get to working on it. Thanks again! :thumbup:


----------



## Xorti7 (Dec 27, 2004)

These are the vac lines engine bay: 
http://users2.ev1.net/~jboykin/vaclines.htm

Mine's similar, it blows hot when the throttle's open. Can't figure it out yet tho. Good Luck.


----------



## Zen31ZR (Mar 24, 2004)

Xorti7 said:


> These are the vac lines engine bay:
> http://users2.ev1.net/~jboykin/vaclines.htm
> 
> Mine's similar, it blows hot when the throttle's open. Can't figure it out yet tho. Good Luck.


Very good post. Thanks for the info. 
According to what I've figured out about vacuum systems in general, the problem usually rests with the canister. 










Might also be the line coming from the plenum. Any vacuum line or canister exposed to the engine compartments heat for 15+ years is going to have problems.


----------



## RackZX (Sep 3, 2005)

Thanks abunch Xorti7 :thumbup: 


Xorti7 said:


> These are the vac lines engine bay:
> http://users2.ev1.net/~jboykin/vaclines.htm
> 
> Mine's similar, it blows hot when the throttle's open. Can't figure it out yet tho. Good Luck.


----------



## gat1954 (Nov 12, 2007)

Vacuum Lines

here's the Vacuum line diagram Site..


----------



## AZ-ZBum (Nov 21, 2004)

gat1954 said:


> Vacuum Lines
> 
> here's the Vacuum line diagram Site..


Good job moron. Nice follow through on a 3 year old thread.


----------



## Paul S. z31 (Aug 12, 2008)

*A/C Problem 85 z31t*

Hey guys, i have the same problem with the vacuum lines. I found the bad vacuum line, the one that runs through the firewall on the passenger side, but when i tried connecting the new line to the old to feed it up underneath and out through the firewall and into the engine bay, the old hose broke halfway. So now i can't seem to feed the new line through the firewall and down to where the tee connector is. Can anyone help me?


----------



## JonJam88 (Sep 14, 2009)

Cool! I needed the diagram.
What an A**!!


----------

