Heater gets very hot and over heats - Hayward Pool & Spa

Not sure how much time you are talking about. The heat you get is from the water in the engine. The heater will not blow hot air till the engine coolant water heats up. The engine water flows through the heater coil under the dash air will blow across the heater coil and give you hot air coming out the vents. Engine has to heat up before you get hot air from you heater.

Was lack of heat in the cabin the only reason you changed the thermostat? Were the radiator hoses hot (or very warm) to the touch before you changed the thermostat? Were the heater hoses hot before you changed the thermostat? Did you get a check engine light and code stating that the engine was not getting (or slow getting) to operating temperature?
Getting heat from your heater depends on a blend door actuator letting air flow through the heater core in the HVAC unit. If your radiator hoses are hot, your heater hoses are hot, and you have no trouble code indicating the engine is not getting to operating temperature, but you are not getting heat inside the car, you need to check your blend door actuator or the control unit for the heater.

Make sure the heater hose is hot with the engine is warm. The heater hose goes into the firewall and into a heat exchanger/ blower fan that will give you defrost and car heat. If the heater hose doesn't get hot you may have a blockage in the hose or at the radiator outlet.

Your thermostat may be stuck open and your coolant isn't getting hot to warm the cab.Here's a link on how to replace,very easy to do.Don't let your pets near spilt coolant,will kill them.

Try this trick take the hoses off the heater core and flush it out with a water hose to get the airout the heater core.don't do it with the car running.goodluck

Check your thermostat. Put a meat thermometer in radiator start engine wait till top radiator hose gets hot it should be 180 or better if not replace. If it does get hot flush the heater core by disconnecting the two hoses and hook a garden hose to it and back flush it. If no heat now your doors are not working under the dash

Check for heat at the heater core at the 2 hoses at the firewall.
If they are hot and the inside doesn't get warm or hot, then there is a blend door problem.
Otherwise, if the heater core isn't getting hot, there is a restruction or clog in the heater core.
The heater core will have to be flushed out or replaced.

if you dont have hot air or hot water then it sounds like you have a hot water coil in you fan unit. The water heater heats both your domestic water and a closed loop for your home heating you may want to make sure the pilot is lit on the water heater. if you cant get the pilot lit by following the insrutions on the water heater you will need to call a heating contractor

FROM LUSTYKID:

Check to make sure your control lever is not disconnected. First

Second:
Check the motor controlling the heat cold/hot DOOR window. Sounds like its in the cold position, thus you are not getting the heat. The door needs to move and shut off the cold intake so that the air is passing through the heater core.

The third item is, although you flush the heater core, it can still be clogged up, in which case you will have to replace it. You probably flush the tanks of the heater core. Think of it as a miniature radiator. The tanks get clean, but unless the hot water passes from one end to the other through the vanes there is not heat, because the heater core is not getting hot.

on the passanger side in the heater box you got the motor for hot and cold trap the motor stick sometime if you whant to try warm up the cherokee put it to heat bang the heater box the motor should move to heat .before normally one day the heat work fine one day no heat that the motor that defective check that out if it not that there a few other thing that i can help you thanks for using fixya pierre