Heater core leak & AC wont work?

hmbkelly · Aug 30th, 2009, 05:40 PM

1997 Nissan Maxima. The heater core started leaking so I plugged off the two hoses at the firewall until I had time to fix. Problem is the ac stopped working at the same time. Fan still blew air, just not cold air. AC pump and clutch seem to be working and I added 134a to system (55psi topside) any ideas why ac not working.

I didn't need to discharge the ac system when replacing the heater core.
Could this problem be related to heater problem or due to bypassing the heater core?

**JNCoRacer** · Aug 30th, 2009, 11:54 PM

It almost sounds as if the intermix door is stuck. Its a flap that opens and either lets air blow across the heater core or the evaporator coil. Unfortunately theres no way to physically check it without removing the entire dash.

Do you have manual or automatic/digital AC controls?

hmbkelly · Aug 31st, 2009, 10:47 AM

Thanks for the reply. That is one of the things I was thinking as well. The door motor moves on the bottom of the heater (and the side direction motor works as well).
You are correct that I can't see if the intermix door is actually moving when the motor does. I hope I don't have to remove the dash again as it is a pain in the butt! I will check it out tonight. Do you think anything in the unit electronic could of failed due to heater core leaking? Thanks again. BTY I have manual controls

**JNCoRacer** · Sep 1st, 2009, 09:43 AM

If the compressor and clutch are engaging, and the blower is on is then its probably more of a mechanical issue than an electrical one.

When you added refrigerant to you AC system did you get readings for the high side as well? And was the system low on refrigerant? It may be over charged.

hmbkelly · Sep 3rd, 2009, 10:08 AM

Just had a chance to check all the cooling and heating doors and they all operate properly.
I didn't get readings on the high side but will as soon as I get the gauge. As for the refrigrant the low side was at 30 and I added enough to bring it to 50 as suggested on instructions. The pressure is at 50 as it was when I left 5 days ago. Because the AC went out when the heater core started leaking it seems they are related in some way. Next I will check the high side pressure and thermo control amp.
Thank for your suggestions.

Dan

Corporate Gifts · Nov 16th, 2009, 05:59 AM

Are you talking about the heater core? Usually if the heater core is bad it will leak inside the vehicle under the dash board and run coolent out onto the passenger side floor. Most of the time you can replace the heater core yourself. It may be hard to get to though. You can usually buy a used one at a salvage if you wanna save some dough. I would buy a new one or rebuilt because you get what you pay for. On the other hand if coolent is leaking from around the manfold then you probably have a manifold gasket that has failed. Again you can replace this yourself with help from a mechanics manuel. Gaskets are not to expensive probably about 10-20 dollars, Also, I would pul the dipstick and make sure you dont have coolent or water in your oil. If you do, then you have a blown head gasket. You can replace a blown head gasket again with help from a mechanics manuel. The head gasket is probably about 40.00. Good luck to you.

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