cool air on driver side, warm to cool on passenger side

ok I recently did a blend door install. Fixed the recirculation door problem but now the passenger side is blowing warm air that eventually gets a little cool. Driver side blows cool air from a Single Zone System.

Before I take the hvac box apart again (and invest in a refrigerant re-capture system because it's $400 to evacuate the refrigerant at the local mechanic) how can this occur? When the temp is set to cold the upper and lower blend doors are supposed to flow air around the heater core to the exhaust which supplies air to both driver and passenger sides.

One thing that comes to mind is my truck is setup for dual zone. that is the duct work is the same for single and dual zone from the factory and the only difference between the two systems is an extra actuator and a split door for the upper and lower blend doors.

This video shows the blend door operation


Any ideas?

 

There is a good chance that you are undercharged with refrigerant.

As you have noted, even though you have a single zone AC system, the same dual zone baffle is used in the housing which splits air flow through the evaporator core. If there is a slight undercharge of refrigerant, the changing from liquid to gas occurs more in one side of the evaporator core than the other resulting in insufficient cooling in the passenger side duct work.

Since I do not know what method you used to recharge the AC system, I would try adding refrigerant first while monitoring the system with a set of gauges.

Also, the early 3rd generation trucks are prone to suddenly expelling refrigerant over the relief valve (usually unnoticed) because of a very infrequent event - the engine fan does not rotate after an engine start and the AC is running with an idling engine. The condenser overheats and pressure builds to relief valve protection pressure and opens. The relief valve is located on the compressor and will usually leave an oily looking mess in the area if this has happened.

- John

 

My 2003 was like that and I brainstormed for a long time until I stumbled onto a statement in the factory shop manual that clearly stated that this very condition (cool to cold on left, warm on right) was the result of an undercharged system. I have gauges so I watched them and added a full can (12 oz) and the system works wonderfully.

Charles

 

Thanks for the pointers Gentleman - off to get a set of guages.

 

Same here - but do not charge with the gauge at the can.
If that low side gauge is used (solely) the system will be severely overcharged*.
To charge by pressure one needs a set of gauges that also shows the high side, take the outside temperature into account and then charge.

*that's a RAM unique that even severely overcharged the low side always shows low at the gauge, about 20psi, rarely more.

 

Always flush the hoses with Freon to not bring any Oxygen into the system. Very important here.

 

Copy that @Ozymandias

 

How do you do that Ozy? have a small amount of freon escaping while you connect to the high and lo ports on the vehicle?

From the web:
With the valve knob closed on the refrigerant canister, connect the yellow hose from the a/c manifold gauge set. With the line connected, open the valve on the can. The next step in the procedure is to bleed air out of the yellow line so that it does not get pushed into the a/c system. Do this by loosening (but not disconnecting) the yellow hose fitting at the top of the manifold gauge set until you hear air hiss out for two seconds.

gauge set arrives tomorrow.

 

Almost like they write.

Your System is still pressurized, so you connect all the fittings to the AC ports and open them, now you have hoses and manifold filled with a mix of Freon (from your Truck) and air - then you open the valves at the manifold, one after another and let the Freon flush the air out of the manifold through the yellow connection to the environment. Then you connect the yellowline and flush the line up to the manifold like they say. Now your manifold and all attached hoses are oxygen free. Half a second is enough time to flush each line, it's fast.
Make yourself familiar with how each valve at the manifold works and which passages it opens to not mess up with it during the process.

Charge is then done solely through the low side port, do not open the manifold passage to the high side with the engine running it could blow your R134a can.

Be careful and slow open the valves to not let oil foam up and reach the manifold. You do not want to loose oil during the process.
The effect is very much like a shaked Coke bottle.

Charge slow and in small steps as the system takes some time to equalize each spray. I always charged liquid phase, can upside-down. Otherwise it takes forever.

And read the chart in the manual for the outside temperature correction values, this is very important as R134A changes pressure massively through Temp changes.

 

You could even do a full charge by weight by venting the system down to 1 psi, which is "empty" and then refill the 16oz.
This is also a way to fill a system lacking a vacuum pump - fill, vent-flush, refill. No air in the system.

Air is an ACs worst enemy.

 

I can attest to that. Over the years, I just dumped a can of freon in, when it started to get warm, with a very slight leaky system.
A few months ago it started to warm up again, but the cheap gauge, that came with the freon said I was severely overcharge, and the needle was almost maxed out. Surely the gauge was off. so, I used another gauge I had. That was pegged too. So, for fear of blowing something up, I bled the system, for a few second at a time, until the pressure was normal. It has worked fine, ever since.

 

Gauges and a vacuum pump are very important to getting the a/c to blow cold! A pocket thermometer also helps with the charging process. I fixed a friends daughters car that wouldn't cool a bottle of water! Pulled vacuum and waited 20 minutes to confirm system was sealed. Filled system while watching gauges cycling and taking into account of the air temps. Also used a carpet dryer fan blowing across the condenser. She can't believe how cold it gets now!

 

I have a leak somewhere -AC systems was refilled by a local shop, they replaced the orifice tube as well. This was 1st week of May this year. Or they didn't fill it correctly.

Freon sniffer and UV light with goggles arriving tomorrow, Gauges today before 10 p.m.

Found this which is the condenser cool down technique that @Topzide describes

 

Most of the time I charge with the engine off. My old Ranger has a slow leak, probably the compressor shaft seal, and it holds R134a all summer and loses it when allowed to sit or not run the a/c. I hook up gauges but after flushing the lines with the 134 I fill thru the low side and use a bucket with about four or five inches of hot water in it to force the 134 into the system. I did this the other day with two cans into the Ranger and then started it up, works great now.

I watch the pressure as I fill it and have been doing this with R12 and R134a for close to 50 years now. I swish it thru the water and then pull it out. As the water cools I just leave it in the water and swish it around.

Charles

 

Ok did a static test - hi side and low side have equal pressure.

added a little over 12 ounces of freon to get the high side to around 225 - 250 psi. service manual calls out 200 to 300 psi @ 80 degrees F for the high side and 25 to 35 psi for the low side. I took a 5 minute video to upload. Here's the script in case it barfs on me. The low and high pressure vary over a 5 minute span. High side goes from 150 to 300, fan kicks on then drops. Low side goes from 10 to 30 then drops when the fan kicks on. The orifice tube frosts when the pressures are low and defrosts when the fan kicks on.
this cycle repeats twice in a 5 minute span. The driver side vents are producing 58 degree F air (should be 45), the passenger side is at 72.

Some history : blend doors replaced last fall. shop reloaded the R-143A - was blowing cold. was winter. Didn't check again until April - not so cool, took it back to the shop, they said the high side was generating too much pressure and replaced the oriface tube. They said everything checked out. Took the wife for a ride and she noticed warm air coming out the passenger side. I cant say for sure whether there was always a temp imbalance between the passenger side and the driver side as Im the only one in the truck 95% of the time.

Some more history : maybe about ten years ago I blew up the AC system not knowing what I as doing - overcharged it. Dealer replaced everything although i dont have the receipts for that. What i do know is that towards the rear of the compressor there is a bunch of dye visible when using a UV light. Blasting it with brake cleaner didnt dissolve it so im thinking it could be pretty old. Or I had one of those events that @petersonj mentioned in the first reply. Directly on the back of the compressor there is a bit of what looks like old oil. would have to scrub it off as its dry.

Using the UV light I see no signs of dye at the exit of the evaporator, around the accumulator or any of the fittings towards the back of the engine. Only near the compressor is where I can see dye.

So I obviously have a leak somewhere as the shop filled the system 1 month ago.

can anyone tell me if the oriface tube is supposed to frost/defrost like that?

Tim

 

Your cycling should be with the ac clutch on and off as the pressures increase. You'll see both the high and low side rise and fall. The tube should stay cold to the touch and not "defrost" as you state. I've gotten to the point to not trust the way most shops charge systems as they're doing by weight only. Total evac of system and let set to confirm that there is no leaks in system. After confirming that there are no leaks, start refilling. Use the started weight amount as guide to not go over. Sometimes it takes a bit less to get good results. Remember that most cans are 12oz. Hope this helps as this is what I've been doing for years on mine and others vehicles.

 

@Topzide thanks for the oriface tube G2. And I've come to the same conclusion as you. I really don't know what the shop did. So I invested in all the equipment to figure it out myself. The first step will be to evacuate and place the system under a vacuum to identify a leak.

I also tried scrubbing the dye off with a 3M scotch pad and some degreaser. That stuff is baked on leading me to believe that its really old. We'll see...

Tim

 

I use the procedure and the bands below in the chart to add to existing charge. I get satisfactory results without evacuating the system.

A/C PERFORMANCE TEST

WARNING: REFER TO THE APPLICABLE WARNINGS AND CAUTIONS FOR THIS SYSTEM BEFORE PERFORMING THE FOLLOWING OPERATION. FAILURE TO FOLLOW THE WARNINGS AND CAUTIONS COULD RESULT IN POSSIBLE PERSONAL INJURY OR DEATH .

NOTE: When connecting the service equipment coupling to the line fitting, verify that the valve of the coupling is fully closed. This will reduce the amount of effort required to make the connection.

1. Perform the A/C System Performance Test found within the HVAC System Test. If no diagnostic trouble codes (DTCs) are found in the A/C-heater control or the powertrain control module (PCM), go to Step 2. If any DTCs are found, repair as required, then proceed to Step 2.
2. Connect a tachometer and a manifold gauge set.
3. Set the A/C-heater control to the Recirculation mode (max-A/C) position, the temperature control to the full cool position, and the blower motor control to the highest speed position.
4. Start the engine and hold the idle at 1,000 rpm with the compressor clutch engaged. If the A/C compressor does not engage, see the A/C Diagnosis chart.
5. The engine should be at operating temperature, the doors should be closed and the windows opened.
6. Insert a thermometer in the driver side center panel outlet and operate the A/C system until it stabilizes.

NOTE: The A/C compressor clutch may cycle, depending upon the ambient temperature and humidity.If the clutch cycles, use the readings obtained before the clutch disengaged.

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Performance Temperature And Pressure

 

The charge is low. Freon flow path through the evaporator cools the driver side first without enough cooling left for the passenger side. I have to do it occasionally due a small leak in my AC system.

I use the procedure and the bands below in the chart to add to existing charge. I get satisfactory results without evacuating the system.

A/C PERFORMANCE TEST

WARNING: REFER TO THE APPLICABLE WARNINGS AND CAUTIONS FOR THIS SYSTEM BEFORE PERFORMING THE FOLLOWING OPERATION. FAILURE TO FOLLOW THE WARNINGS AND CAUTIONS COULD RESULT IN POSSIBLE PERSONAL INJURY OR DEATH .

NOTE: When connecting the service equipment coupling to the line fitting, verify that the valve of the coupling is fully closed. This will reduce the amount of effort required to make the connection.

Perform the A/C System Performance Test found within the HVAC System Test. If no diagnostic trouble codes (DTCs) are found in the A/C-heater control or the powertrain control module (PCM), go to Step 2. If any DTCs are found, repair as required, then proceed to Step 2.

1. Connect a tachometer and a manifold gauge set.
2. Set the A/C-heater control to the Recirculation mode (max-A/C) position, the temperature control to the full cool position, and the blower motor control to the highest speed position.
3. Start the engine and hold the idle at 1,000 rpm with the compressor clutch engaged. If the A/C compressor does not engage, see the A/C Diagnosis chart.
4. The engine should be at operating temperature, the doors should be closed and the windows opened.
5. Insert a thermometer in the driver side center panel outlet and operate the A/C system until it stabilizes.

NOTE: The A/C compressor clutch may cycle, depending upon the ambient temperature and humidity.If the clutch cycles, use the readings obtained before the clutch disengaged.

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Performance Temperature And Pressure

 

Yep - I ran the same procedure @jghflys and still noticed the temperature differential between the drivers side and the passenger side. The driver side vents are producing 58 degree F air (should be 45), the passenger side is at 72. I'll be heading to europe on Saturday for a business trip so the vehicle will sit for about 2 weeks. When i get back I'll hook up the gauges and see where we are at.