93 plymouth voyager low heat

Dont Assume anything til u hav a shopmanual that givs engine specs and details. Partstore or librarya

Given the age of the car I'd bet the heater matrix is blocked up.
When the car is warmed up look down the back of the engine and trace 2 hoses about 1.5 in diameter heading through the bulkhead. if these are roughly the same temp. ie hot then the matrix is blocked.
Even with correct coolant 5-8 years / 80k miles is the norm for these.

depending on the particular model and facia layout this can be a mornings work for a good diy or a major task for a competent mechanic.

If the vehicle has been run for any time without the correct level of antifreeze / summer coolant then the matrix will block up.

I presume you have checked the thermostat? When the car is warm, feel the upper and lower main rad hoses. The lower should be cooler than the top. Does the heat reflect the actual engine temp? Does the gauge read low all the time? Is the thermostat stuck open and the engine temp is low?

Finally, if you think the coolant is hot enough and the small hoses are as hot, are the heater flap controls working properly?

Both of the hoses at the heater core should be hot. If one is cold the heater core is plugged. You can think of it this way. If the thermostat was stuck closed and you checked the upper and lower radiator hoses with the engine hot the upper hose would be hot and the lower hose would be cool because there is no flow. If you check the hoses with a properly working t-stat both hoses will be hot when the t-stat is open and coolant is flowing. Let me know if you have any questions and I'll do my best to answer them. Thank you for using FixYa.com!

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

Follow the upper radiator hose from the radiator to the engine and you will see a 2 bolt housing.drain some of your coolant to get it lower than this housing and then remove the hose and 2 bolts.pry out the thermostat and clean the area.do not let any debris enter the engine.install the new thermostat exactly as removed and a new gasket with the housing.reinstall the hose and top up your coolant.let the engine warm to operating temp and have the heater on inside the vehicle with the fan off.dont forget to test drive to make sure its ok

If the thermostat was installed backwards, it won't open when the engine heats up. The spring/sensor should go toward the engine and the valve plate goes toward the radiator. If the hoses stay cold, it points to no water flow as above. Hope this helps!

If you were to take the upper radiator hose off the engine, and look into the resultant hole, you would see the thermostat.

The thermostat on all cars blocks water leaving the engine and going to the radiator, until the thermostat warms up enough to open.

While the thermostat is closed, water circulates through the heater hose, straight back to the inlet of the water pump. This circulation prevents hot spots, distributing the heat evenly to warm the engine up, and also brings that warmed water to the thermostat.

When the t-stat gets hot enough to open, water leaves the engine instead of circulating through it, and that allows cool(ed) water to flow from the radiator through the bottom hose to replace the water that left through the upper hose and t-stat.

The stub that the upper hose attaches to on the engine should be part of a small housing that is bolted to the engine. Removing that housing is how you remove the t-stat.

Your electric fan is probibly not running.Fan switch,fan relay or the fan could be bad.If it is getting hot and you pop the hood you should hear the fan running.

could be a cracked block engine.what i would do is put a tarp or old sheet down park vehicle on it and wait then when you check you can look on old sheet to see where its leaking and it will give you an idea where to look for the leek if it was head gasket youd have sludgey looking whitesh foam in the oil

The thermostate will be found under the upper radiator hose where it meets the engine. With the engine cool disconnect your battery ground (safety sakes) Down low on the radiator you will find a petcock (valve) place a bucket under this and open draining out @ 1 gallon or so of fluid. Remove the upper hose and the the thermstat housing (2-bolts) under it you'll see the thermostate, remove and clean all surface of old gasket. Install new thermostat and new gasket, reassemble, add fluid and place battery ground back. Run the engine for a moment and watch the fluid level after one minute or so add more fluid (if needed) and install cap. Get engine to temperature and watch for leaks. Next two days or so I'd monitor the fluid level in the over-flow and add as needed. Again watch for any leaks. The job itself should only take you an hour or less.
Please let me know if this assited you.
Thanks,
Tom

If you changed the thermostat yourself and have noted that the lower radiator hose is cooler than the upper radiator hose, you may have installed the thermostat incorrectly or have purchased a faulty thermostat. A lower radiator hose that does not get hot (or as hot as the upper radiator hose) is a direct indication of a faulty thermostat. Please vote for this solution if you found this to be helpful. Thanks,