My heater blows cold in my 1989 GMC 350 engine. The thermostat has been changed, the fan blows. I can hear the door opening. The engine comes up to temp. Are the hoses to the heater core supposed to be hot? They are not. I replaced the intake last week. Is there something that I might have missed reconnecting. I checked all the vaccum lines. Thank you for your help.
both hoses are cold. The one hose to the intake is hot at the end on the intake, but the rest of the hose is cold.both hoses are cold. The one hose to the intake is hot at the end on the intake, but the rest of the hose is cold.
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Ok there is a few things might be happening...first did you make sure when you put the intake gaskets in there was No ports plugged or covered...second is...are both heater hoses Cold or is one hot and other cold...if so you have a air lock in the heater core...if this is the problem you need to lossen off the cold one till antifrezze comes out.
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check antifreeze level add if low, and check intake heat control valve on ps side of intake if its locked shut it can be removed and a water pipe nipple put in place of it and the heater hose reconnected..if the water pump is good, it should give heat this valve should be on the intake with a heater hose connected to it..and its vacuum operated but will jam shut with age and cold weather..good luck..
Check for correct coolant mixture. Also you could have a thermostat that is stuck completely open causing it to flow straight threw the engine block, cylinder heads, heater core, an radiator without stopping long enough to heat the coolant up to provide cab heat. It could also be a clogged heater core. Or a blend door on the HVAC box that is not allowing the heater core door to open. Hope this helps.
Check coolant level. if ok then see if engine comes up to temp. 190+ at thrmostat housing. If not, replace thermostat. If thermostat is ok, feeel heater hoses. If one is hot , and the other cold, then remove both and flush heater core. If both are hot, suspect blend door problem in heater box. probably need pro help for that.
I have written a tip on this.
You may have a couple of problems. I would first replace the thermostat, and make sure you have the proper coolant(ant-freeze) level.
Please let me know how it goes and if you need further help I am here.
hello , sounds like an air lock in coolant system , drain system and re fill very very slowly , if you think you are filling it slowly enough slow it down even more , also replace thermostat to ensure its opening and closing properly , hope this helps
Check blend door motor for proper operation (vacuum operated) if necessary, detach arm from heater box and move by hand. If you have heat then, change motor! You are reaching operating temp for engine, right? If not, thermostat is stuck open... Change.
first, make shure that the water level in the radiator is apropriate, then ck the thermostat for oppening and closing(you wont have a heater if the thermostat is constantely open) ck the 2hoses that suply hot water to the heater core, both hoses must be hot when engine is runing .if one off the hose is cold ,the hot water is not circulating to the core and back to engine .ck the valve , see if you can by pass it and see the results if you have heater , replace the valve. nicolas
both hoses are cold. The one hose to the intake is hot at the end on the intake, but the rest of the hose is cold.
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