My 1994 Xj AC was leaking so I did a total gasket and rings and head change for it , filled it with Freon , test it again no more leaks.
But the cool air is not cold enough from the vents , it did 15 degree Celsius (59 F) on idle and 12 Celcius (54 F) when accelerating.

The shop said i must install a Ball Valve on the heater core return hose to close the water in summer and open the valve in winter.

I read lots of posts and im confused some said both hoses some said only the lower thin one and some said the upper thick one.

Which one should i install the valve on please?
Any effect of the engine temperature/coolant if this is done?

The heater core is brand new i just replaced it 2 month ago,
My xj is 1994 country edition.

Any help is appreciated, thank you

 

You can put a manual valve on either of the heater core hoses--if fluid can't flow through it will just stop moving (fluids don't compress). The biggest potential negative effect is having crud build up in the heater core from letting the coolant set, but you can avoid that by opening the valve periodically. Might be worth the effort to reinstall a heater control valve, but they are pretty poor design and fail often.

 

Sounds to me like the A/C shop didn't do a very good job. Did they check all the air control valves in the dash ?

On my 88 & 96, heat works great, so does A/C, and no ball valves on them....only the stock old maybe not working so well heater control valves. Does your still have a heater control valve on it ?

To me, their logic is the same as them fixing the A/C in your house, and then telling you you have to turn off all the lights, close all the curtains, turn off clothes dryer, turn off the fridge/freezer, and don't use the oven, cuz they produce too much heat.

It's just masking the problem.



If you put the valve in, put it on the return side, so the heater core stays full and can't fill with air pockets, which can hasten corrosion. On the supply side, it will have a lower pressure on it until the t-stat opens, and could let air get in the heater core.

 

No the control valve was removed by the previous owner and both hoses run directly.

The air flow from the vent is good , it is not weak so blower motor is working correctly.

When the engine is cold in the morning the AC flows cold air perfect but when the engine gets warm/hot cold air is a bit weak.

I also replaced the radiator 2 weeks ago and installed a 180 thermostat with a new housing (found out there was no t-stat in it, the previous owner removed it), did a flush and the radiator shop filled the radiator with 100% tap water without the coolant saying its better without it for engines running over 250k miles.

The return side hose is the thin one right?

 

Ben Dover Radiator and AC, amazing !!

 

"...and the radiator shop filled the radiator with 100% tap water without the coolant saying its better without it for engines running over 250k
[/quote]

This is true. For the shop. It wont be too long before you're back buying another radiator, water pump, thermostat and heater core after your rusts to hell.

Please get some coolant in there and then figure out why the ac is under performing.

 

Always run anti-freeze & water....alone, they work about the same, but together, due to the chemistry behind it, they work much better.

Water alone is plain old crap, and them trying to get more money from you on future repairs.

Put a heater control valve in it, add antifreeze, and never go back to that radiator shop, then you should be fine.

 

OK will put a manual valve and add anti freeze. Must drain the radiator and add 50/50 water and coolant right?

 

Well, add straight anti-freeze to GET a 50/50 mix......if you add the premixed 50/50 stuff they sell these days, you won't get it right unless you drain all of the water out.

 

The tap water has to go anyways. Wants distilled and straight antifreeze or 50/50 premixed.

 

So I must drain the radiator first then add antifreeze and water right?

 

Yes. Distilled water and straight antifreeze.

 

You shouldn't need to shut the heater core "off" to have decent AC. We didn't need that from the factory, and we don't need that now either.

 

Actually, you did. When you switch the temp control lever, it shuts the heater control valve, which blocks flow to the heater core, and that lets the heater core cool down.

Later models use blend doors to shut off the hot air, so it doesn't mix with the cool air.


I know that's what they say, but I've never used distilled water in ANY of my vehicles, and never had any issues from it either. Battery maybe, radiator, no.

 

That heater control valve in earlier models very frequently gets deleted because it ages, breaks, costs way too much to replace, and does nothing but lets coolant stagnate in the heater core which is never good in the long run. It is entirely unnecessary. To my knowledge, there's nothing especially "blendy" about 97+ hvac boxes.