AC blowing hot air

[Truman]

My system was leaking coolant pretty bad. I replaced the lower hose and it still leaked some. I put some radiator sealant in and the leak stopped. I recharged the AC coolant about a month ago.

My dash is still blowing g hot air. What could it be? Heater core clogged?

When I checked the coolant levels last there was alot of pressure when I turned the radiator cap.

 

[highdesertranger]

as for the radiator, flush the system immediately and fix the leak. stop leak is about the worse thing you could do.

what is a lot of pressure? your radiator cap is rated for a certain pressure that's what it should be. get a cooling system pressure tester and check the cap and then find and fix the leak with it. where is the leak? get that stop leak out of there.

the heater core has nothing to do with the AC blowing hot air. you are probably still low on Freon.

highdesertranger

 

[Truman]

I think the leak was coming from the engine right above the hose lower hose. It was dripping down onto the hose.

The hose would gush out coolant when i squeezed ot which is why i replaced that.

The gauage on the freon says good.

 

[tx2sturgis]

Stop-Leak will cause more problems than it will solve.

As far as your A/C, you need to check a few basic things and get back to us with the answers.

With the hood up, engine idling, blower on, temp control set for cold, turn on the A/C...does the compressor engage?

If so, does the engine speed decrease slightly? 

After its been running for a couple of minutes, CAREFULLY, and avoiding ALL moving parts...touch the refrigerant lines, one should be quite warm, and one should be quite cool.

Let us know.

 

[B and C]

Check the hole on the bottom of the water pump for coolant leak. When the seal goes on the water pump, there is a hole on the underside that coolant will leak out of.

Your dash blowing hot air is unrelated to your engine coolant leak. Probably low on freon. Check that the A/C compressor engages when turned on as stated above.

 

[Truman]

Yea. So I did this. And the engine didn't bog down at all when I turned the AC on. And one line got warm the other was ambient temp

 

[B and C]

Yep, sounds like freon is low at a minimum.

 

[bullfrog]

Once you get the AC working properly you need to keep an eye on your temp gauge as you will have more heat to deal with under the hood. Is the heater valve (hot/cold) closed? It is usually in the smaller hoses going to the heater core just before they go through the firewall under the hood and either cable or vacuum operated.

 

[Truman]

That nose valve broke and I can't find a replacement. It's stuck on AC. But the cold/heat works.

My van runs cold usually. I think the heater core needs flushed.

 

[highdesertranger]

again the heater core is not causing the AC not to blow cold.

did the compressor engage when you did the AC test?

highdesertranger

 

[bullfrog]

Sounds like the AC is the least of your problems. Keeping the coolant in the engine and the cooling system working properly will greatly influence how long your engine will last. Flushing and pressure checking the system should be a priority.

 

[highdesertranger]

x2 what Bullfrog said. get that coolant system fixed. and no stop leak. and no mickey mouse repairs on it. AC is a luxury item. highdesertranger

 

[Truman]

Aye aye Captain

 

[Truman]

So I figured out the water pump is bad. I got a replacement im going to work on tomorrow.

Now prior to all this my engine would run on the cold side. Is that a heater core issue? I plan on flushing it out while i have it apart. But how would i know if the heater core needs replaced so I can do it all in one job.

 

[bullfrog]

If the hot cold valve is stuck open and water flows through the heater core all the time then the engine will take a little longer to warm up and run a little cooler depending on the thermostat’s opening temperature. If the heater valve is broken now would be the time to deal with it as well. Most temperature sensors won’t read correct temperatures unless they are submersed in coolant, if you have been running the motor with little or no coolant it should be checked also as it may have been damaged also and the temperature gauge may be read incorrectly. Back flushing the system is necessary since stop leak was used and if the heater core is plugged up it should be apparent. Since the antifreeze is costly the whole system should be checked out as in hoses, sending unit, thermostat, heater controls, heater core and radiator.

 

[highdesertranger]

if the engine was running cold more than likely it was the thermostat. but the important question is,

What do you consider cold? we need an actually temp here not a guesstimate. if your gauge only has a C and H on it there is no way to tell.

you test the heater core just like the rest of the cooling system with a pressure tester.

did you get rid of that stop leak. if the water pump was leaking out the weep hole stop leak won't fix it anyway.

highdesertranger

 

[Happy Camper]

HDR and others can tell you better than I. But since you're replacing the water pump, maybe you should consider also replacing the timing belt/chain if your vehicle is higher miles or is nearing the recommended change

Better to do it while the water pump is off since you have to remove it to change the timing chain when you do it. Just a thought.

 

[Truman]

Thanks for the feedback.

I got a new thermostat and drivebelt and im going to flush the heater core. I should have this all done this weekend.

The temp gauge only goes up to about 25% when it's running. The vents blows warm air but not really hot like it should be.
I always put the repair off as this van is in a constant state of repair/modification and Im always juggling priorities. So im thinking now is a good time to address this issue.

Yes. I flush out the old coolant and have new coolant waiting

 

[bullfrog]

Okay your radiator has an upper and lower large rubber hose attached to it which allow coolant to from the engine to the radiator and from the radiator to the engine. If the thermostat is stuck in the closed position the upper hose gets hot in just a few minutes running and when you shut off the engine the coolant in the top hose boils and fills the coolant overflow catch bottle that is attached by a tiny hose that is attached to the radiator by the cap sometimes boiling out of the overflow bottle causing the coolant to be low once it cools down over night.. The lower hose will be cool or only slightly warm. If the thermostat is stuck open or has a faulty seal the coolant with the engine running will circulate through the radiator continuously causing both upper and lower hoses to be both the same temperature and take a longer time till both heat up. Unless you drive some distance the engine will seldom completely heat up and the level of coolant in the overflow catch bottle will only change slightly. The heater core has it’s own hoses directly to the engine. One supply and one return, smaller hoses, controlled by a valve they heat up with the engine and start flowing coolant as soon as the engine starts if the valve is open through the heater core as well. The heater core is basically just a small radiator with an electric fan. After a few minutes of the engine running with the valve to hot and the fan turned on you should feel warm air coming out the ducts inside of the vehicle. If it is plugged the heater core inlet hose at the firewall will be warm and the outlet hose at the firewall will be cool. After you back flush and fill the system be sure the heater valve is open and run the engine to insure it fills with coolant as well. The overflow catch bottle should be filled with coolant to the “Full Hot” mark. Be sure to check the radiator and the overflow bottle the next day after cooling over night before you start it to make sure the radiator cap is allowing coolant to be sucked back in and the system has no leaks so it can. The coolant should be completely to the top of the radiator and maybe even run out a little when you open the cold cap if you are on a hill. The overflow catch bottle coolant level should be on the “Cold Full” mark. Check both the radiator and over flow catch bottle in the next few mornings while the engine is cold before starting to make sure all is well. Hope this helps.

 

[Truman]

Yea big help thanks.

My mode valve is broke. Its stuck on AC. I cannot find a replacement anywhere. Id even take one out of a used vehicle at this point.

I have a 93 chevy G20 5.7l. Id even offer a 20 dollar finders fee if someone could help me locate the damn part.