88 Jeep Cherokee

[hypermaxed]

I have a question I have a jeep that the heat won't blow out when I turn it to heat it will hardly blow any air on vent either I was wondering what this could be I switched the hoses on the heater core they heat up now but still not hot air... any suggestions?



Thanks

Corey

[capt. apathy]

if both hoses are getting hot then it's likely that you have water circulating through it. so this only leaves problems with the airflow side of the system.

the lack of air flow could just be caused by a fan going out, or a switch problem.

but a fan wouldn't explain the lack of warm air.

it could be the control wires, or a vacuum hose (I'm not sure which the jeep uses, since thats one system I haven't had to work on with this vehicle) that runs the dampers in the duct system. vacuum hoses can get holes or come unplugged, and the maual wire controls can break or become unhooked or bound up. this could cause the damper that selects if the air goes through the heater or the a/c could be stuck in the a/c position, and your air never goes through the heater core.

or it could be a clogged up heater core. the outside not the inside. if it's been exposed to a lot of dust and dirt it could have just clogged up between the fins and restricting airflow. that could restrict the flow of air and the air that did get past, would have gone around the core and not through so not pick up the heat. this could also be in combination with a fan problem. restricted airflow, making the fan work harder, plus the same dirt that clogs the core is likely gumming up the motor.

so some questions-
1. the air flow is weak, but is it weaker on low, or is it about the same no matter what speed it's set to? if it's always the same I'd look at the fan switch, it may just be sending a low speed signal regardles of switch position.

2. you said the fan is also weak on 'vent'. but what about a/c? does it make a difference if it's set to 'cold ' instead of 'hot'? is there any settings where the fan does blow strong?

[MissyJ]

I have the same thing!!! I took it to a Jeep dealership, they said it was the fan switch. 3 hours after they put a new one in, it quit! We tried redirecting the wiring to bypass the switch, and it seemed to work for a short while, but again quit...
One thing I have noticed prior to the fan problem is that the stereo components seem to affect the flow with the heater, and when it seems to short circut... There is definately a problem with the wiring.
I have been on a few sites for Jeep recalls, and our year seems notorious for wiring defects...
Let me know if you get it fixed, AND HOW!!!