No A/C in the City

[ford33]

Ok so it's starting to get hot so this problem is getting annoying now. If I am driving down the freeway my A/C works fine, but once I get in the city and am doing a lot of slow driving or idling on a day when it's like 80 or 90 degrees out my A/C stops blowing out cool air.

One day I got a recharge kit at Pep Boys, hooked it up to the Low line, and the gauge read that it was fully charged.

Anyone know what's wrong, have an opinion, or suggestion?

Thanks.

 

[imp]

A/C Condenser.............

Possible reason: If you have the spin-out type fan with a viscous type fan clutch, it may not be driving your fan sufficiently to cool the refrigerant in the condenser coils up front.

While the vehicle is moving forward, the condenser is cooled by normal air flow through it. While standing still, if fan does not draw enough air through condenser to cool regrigerant, warm air comes out of the outlets in the vehicle.

On vehicles with electric fans, they often over-ride the fan thermostatic control to make fan ALWAYS ON if A/C is on. imp

 

[97 EB Mike]

Silly thought, but I don't know what your experience level may be...

The first time I charged ac, I didn't start the engine. So with the gauge hooked up, it showed far more pressure on the low side than was necessary. Also, ambient temp plays a part in the psi of a fully charged system.

I don't know if that would explain the ac working at freeway speeds and not during city driving, because, frankly, my experience with ac is minimal. Just a thought...

 

[ford33]

So if I were to add an electric fan this might help my situation?


I did have my car on and ran it for a little while before I tried charging the A/C. I watched the gauge for about 10mins and it stayed the same.

 

[Gus Gorilla]

imp is dead on for this one. If it cools good at highway speed but sucks when at low speed or idling then your fan is not pulling enough air. It's possible your condenser(radiator looking piece in front of the radiator) is screwed. But much more likely you have an airflow problem because higher speeds correct the problem.

The condenser removes the heat from the system. If it cannot remove the heat you get poor cooling. Higher speed = more airflow = more heat removal = better cooling. Airflow problem. A correctly operating electric fan will correct this. Also a correctly operating conventional fan will correct this.

If you feel the need to prove this out in your driveway then proceed as follows. Run the truck to operating temps. Park and let it idle. Feel your vents get warm and poor cooling. Now spray a garden hose in the condenser to cool it off. The air from the vents will become cool again while water is flowing. This is the best test to do at home for this and proves that the condenser cannot remove heat.

 

[imp]

Gosh, I bet the Gorilla would be one fine guy to have around on your side when a bar room brawl erupts.......... imp

 

[ford33]

Any suggestions for an electric fan I could add on easily?

 

[imp]

Electric Fans?

Any suggestions for an electric fan I could add on easily?

In my book, electric fans are for the "rice burners". The most foolproof system for my money has proven to be the "spin-out" mechanical fan clutch, used with a metallic fan blade. Ford does (or did) that on pickups; Explorers I have seen use a plastic fan blade with the viscous clutch.

Just my 2 cents. imp

 

[ford33]

In my book, electric fans are for the "rice burners". The most foolproof system for my money has proven to be the "spin-out" mechanical fan clutch, used with a metallic fan blade. Ford does (or did) that on pickups; Explorers I have seen use a plastic fan blade with the viscous clutch.

Just my 2 cents. imp

I checked and I have a metal fan...I don't know what kind of fan clutch it has.

 

[ford33]

Is it possible that my fan clutch has gone out? How would I test that?

 

[imp]

Yes, It's Possible!

Is it possible that my fan clutch has gone out? How would I test that?

The clutch itself is filled with a special silicone material which gets thicker as it gets hotter. Therefore, being like a little "torque converter", the silicone allows "slip" between the spinning engine and the fan blade, when the air coming through the radiator is relatively cool. As it gets hotter, the silicone thickens up gradually, allowing more "coupling" to take place between the spinning clutch, and the fan blade fastened to it. This is a simplified description, remember; the high-quality clutches have additional features (thermostatically-controlled internal vanes), which we are skipping over here.

Usually, the silicone fluid gradually leaks out of the clutch; this can often be seen on it, as it collects dirt. So, the clutch fails gradually, not all at once, (usually), so overheating of the engine may not be evident, as the forward motion of the vehicle pushes enough air through the radiator to keep the engine from overheating. If it's "on the brink", however, it is likely the A/C will be affected (blowing not so cold).

Test: 1. Look for evidence of the fluid leakage on the clutch. If it's there, replace the damn thing!
2. If no leakage, start engine cold, allow it to idle, and as it reaches operating temperature, the clutch will, if operating properly, begin driving the fan gradually. You can feel this by carefully checking the temperature of the air coming through by placing your hand behind, but not close to, the back of the fan area, high enough to avoid belts! When the engine is quite hot, the clutch should be driving the fan enough, even when idling, that the air it's pushing will feel uncomfortably hot to your hand. If this is not happening, the clutch is not operating properly. In addition, if your hearing is good, you will detect the sound of the fan spinning faster as the engine gets hot. A slipping clutch with hot radiator will throw little hot air.

Try this, and let us know how it works out. Plenty of us may still regard these clutches as "magical"! imp

 

[jcwaters1]

my '98 has this problem. plastic fan, but it always spins. there isnt a time it's running, hot or cold, when the fan is off. why would this be? also, what do i do if it isnt pulling enough air through to cool the condenser?

 

[ford33]

The clutch itself is filled with a special silicone material which gets thicker as it gets hotter. Therefore, being like a little "torque converter", the silicone allows "slip" between the spinning engine and the fan blade, when the air coming through the radiator is relatively cool. As it gets hotter, the silicone thickens up gradually, allowing more "coupling" to take place between the spinning clutch, and the fan blade fastened to it. This is a simplified description, remember; the high-quality clutches have additional features (thermostatically-controlled internal vanes), which we are skipping over here.

Usually, the silicone fluid gradually leaks out of the clutch; this can often be seen on it, as it collects dirt. So, the clutch fails gradually, not all at once, (usually), so overheating of the engine may not be evident, as the forward motion of the vehicle pushes enough air through the radiator to keep the engine from overheating. If it's "on the brink", however, it is likely the A/C will be affected (blowing not so cold).

Test: 1. Look for evidence of the fluid leakage on the clutch. If it's there, replace the damn thing!
2. If no leakage, start engine cold, allow it to idle, and as it reaches operating temperature, the clutch will, if operating properly, begin driving the fan gradually. You can feel this by carefully checking the temperature of the air coming through by placing your hand behind, but not close to, the back of the fan area, high enough to avoid belts! When the engine is quite hot, the clutch should be driving the fan enough, even when idling, that the air it's pushing will feel uncomfortably hot to your hand. If this is not happening, the clutch is not operating properly. In addition, if your hearing is good, you will detect the sound of the fan spinning faster as the engine gets hot. A slipping clutch with hot radiator will throw little hot air.

Try this, and let us know how it works out. Plenty of us may still regard these clutches as "magical"! imp

The fan clutch looks spotless. I did the cold start test and the fan seems to be working ok.

Would replacing the thermostat and coolant help? I have 175k miles now and I don't know if either of those have ever been replaced. I got this vehicle from my grandfather, who I know did basic maintenance like oil changes. I cannot recall him ever saying anything about doing a flush or replacing the thermostat though.

My temp gauge always reads right below the half way mark when the engine is hot, so I have always thought it should be ok, but maybe not.

 

[ford33]

Does anyone know what the air pressure is supposed to be on the low a/c port when it's like 100 degrees out? I think I am going to try to recharge again.

 

[imp]

my '98 has this problem. plastic fan, but it always spins. there isnt a time it's running, hot or cold, when the fan is off. why would this be? also, what do i do if it isnt pulling enough air through to cool the condenser?

There is always some friction in the fan clutch which keeps the blade spinning along with it, even when it's "seeing" cool air. So, the fan does move some air when the engine is still cold, but very little.

The calibration built-in to the fan clutch should be such that it is intended for use with an air conditioning equipped vehicle. If the clutch is not operating at it's design level, this can account for poor A/C performance. Generally speaking, if the weather is hot, that is, ambient air temperature is fairly high, perhaps 80^ F. or more, if the engine is allowed to sit and idle with the vehicle standing, if the fan clutch is not up to par, the engine will overheat. If it does not overheat under such conditions, chances are the fan is doing adequate cooling to operate the A/C fairly well. imp

 

[imp]

The fan clutch looks spotless. I did the cold start test and the fan seems to be working ok.

Would replacing the thermostat and coolant help? I have 175k miles now and I don't know if either of those have ever been replaced. I got this vehicle from my grandfather, who I know did basic maintenance like oil changes. I cannot recall him ever saying anything about doing a flush or replacing the thermostat though.

My temp gauge always reads right below the half way mark when the engine is hot, so I have always thought it should be ok, but maybe not.

I should have mentioned, leakage from within the clutch does not ALWAYS happen, when one quits working. It's thermostatically-controlled vanes may no longer be working properly, without silicone leakage, and this condition also constitutes a failed clutch. "Cheapie" fan clutches do not have the thermostat device; Ford OEM-supplied clutches always do; they cost more to replace, of course. The thermo.-cont. clutch may be easily identified by a half-dollar-sized coiled spring attached to the FRONT face of the clutch. A vehicle having a shroud surrounding the fan & clutch assembly may not allow viewing the front of the clutch, however.

This spring device is attached to a center axle pin which protrudes through the front face of the clutch; heating & cooling of the spring causes it to rotate that pin, thereby varying the angle of impingement of the silicone fluid within,against the driven vanes. This controls the fan "driving effort" in addition to the fluid's negative temperature/viscosity properties. imp

Edit: Engine coolant thermostat- if it is stuck "open", no effect should be imposed on the A/C operation. If it is stuck "closed", or nearly so, the engine should run hotter than normal, and the A/C certainly might be affected. If the cooling system is completely filled, with no "air space" in the top of the radiator, the age/quality of the coolant itself should have no effect on the amount of cooling effort obtained. The bad about old coolant is that as it becomes acidic with age, it attacks vulnerable metallic parts, like aluminum, cast iron, too, but more slowly.

 

[Gus Gorilla]

Your coolant in the radiator and the thermostat will only cause you a problem with A/C if you have an engine cooling problem. If your not overheating then it's not a factor.

(As a side note if you don't know the last time it got coolant then either test it or flush it. But not for the A/C's sake.)

For the low side pressure if the system is not running and the engine bay is cooled off to somewhere equal to your outside air temp the PSI will be in the ballpark of the temp in degrees F.
ex. At 80 degreesF outside with a system not running you would have near 80PSI. At 100F the two will start walking away from eachother. But if you measure at rest and have 60PSI for example then it's low. If you have 130PSI then either A. the engine bay is hot from driving or B. it's overcharged.

If your system is still working as you originally described then it is likely charged correct.
I'm tellin ya'... shoot cold water through your condensor and it'll cool like a dream.

 

[97 EB Mike]

Does anyone know what the air pressure is supposed to be on the low a/c port when it's like 100 degrees out? I think I am going to try to recharge again.

With the system running you should be seeing 50-55 psi on the low side.

Also a question to further my knowledge on the subject for Gus or Imp, or anyone else following along... If low coolant can be responsible for overheating an engine with a properly operating fan, and with higher speeds the engine runs cooler because of more airflow, could the same be said for low 134 undercooling with a properly operating fan, and higher speeds creating a cooler ac because of more airflow? I'm not trying to sound like a jerk here, so please don't take it that way. Just trying to learn something along the way...

 

[ford33]

I added some refrigerant to the system. It's 103 out side and I have a pressure reading right in-between 50-55psi. It still doesn't seem to be blowing that cold.

I have sprayed cold water on the condenser and yes it did start blowing colder air then normal while at idle.

The reason I added more refrigerant was because it didn't seem like the a/c was even as cold as it should be while I'm on the freeway.

I'll drive it around a couple days and see where I stand. It still seems like I could add a little more refrigerant. I have two different gauges and both of them read something different lol

 

[imp]

With the system running you should be seeing 50-55 psi on the low side.

Also a question to further my knowledge on the subject for Gus or Imp, or anyone else following along... If low coolant can be responsible for overheating an engine with a properly operating fan, and with higher speeds the engine runs cooler because of more airflow, could the same be said for low 134 undercooling with a properly operating fan, and higher speeds creating a cooler ac because of more airflow? I'm not trying to sound like a jerk here, so please don't take it that way. Just trying to learn something along the way...

Let's be sure of definitions here. "Coolant" is the stuff in the ENGINE. Refrigerant, or 134a, is the stuff in the A/C system. Surely, a low level of either will cause malfunction of the engine, or the A/C system.

I'll throw this out, but don't take it for gospel in all cases: Ford in recent years has had it's A/C compressors fitted with a relief valve mounted right on them, to prevent compressor damage from over-charging, or high-pressure resulting from failed components like fan clutches. The relief valves I have seen are cylindrical, about 2 inches high, and 3/4 inch in diameter. If your compressor has such a relief valve, it is unlikely you will damage it by overcharging with refrigerant. PLEASE BE AWARE, however, that I am NOT condoning blindly adding quantities of refrigerant to obtain better cooling effort. Use the proper gauges and keep high-pressure side within limits. imp