Air Conditioner Vacuum Doors Close with Acceleration

Jeep Cherokee, A/C Vacuum Doors Close with Acceleration

Q: Its 1988 Jeep Cherokee with a 4.0 engine. The problem is with the air conditioning doors changing position to vent upon acceleration. The engine and accessories feel good and are running great cruising down the road, except during acceleration. When the engine drops the vacuum level, the A/C unit controls lose vacuum supply and the doors shift to their neutral positions. When we reach cruising speed with traffic, the vacuum comes back in and pulls the doors to the intended position to get that good cold air back in your face. We've visually checked the main vacuum lines from the intake manifold port through the reservoir under the front bumper up to the firewall. Thought I would ask if this is a recognized problem before I bend over and go through the dash, emissions lines or 4X4 systems.

A: If the vacuum lines and vacuum reservoir are not damaged, you have a sticking or missing check valve in the vacuum supply to the vacuum reservoir. The vacuum reservoir is just what its name implies, a storage device for vacuum. The engine creates vacuum. The vacuum is an energy that is used as a power source to operate different emission controls and accessories like the controls for the ventilation system. There are times that an engine does not create a good supply of vacuum. Because of this the vehicle manufacturers install reservoirs to store vacuum. The hose from the engine or the reservoir itself will have a check valve that blocks the loss of vacuum back to the engine. Why is this? When accelerating, the amount of vacuum created by the engine drops to a level that will no longer power any emission controls or provide for control of the ventilation system. The reservoir is designed to hold enough vacuum in storage to maintain control under most driving conditions. If the check valve fails the vacuum reservoir will lose vacuum so quickly that there will be none left in reserve. The result? A loss of control of vacuum operated devices.

Violent Shaking Noticed on Jeep

Vehicle shakes violently while driving

Q: I just bought an ‘87 Jeep Cherokee from a guy I know and while driving it home it began to shake violently almost to the point of losing control. It will stop and restart again but does not seem to be at any particular speed. Any suggestions?

A: I would suggest inspecting the steering and front end components of the vehicle. There is one part in particular, called the steering stabilizer that should be checked over closely. The steering stabilizer is basically a shock absorber for the steering. This not to be confused with the shock absorbers for the suspension. The mass (steering and suspension) in the front end of Jeeps has a frequency problem, meaning that as the vehicle is being driven down the highway a sort of vibration develops. The steering stabilizer absorbs/deadens this vibration so it is not delectable. If the stabilizer is worn it can no longer prevent the front end shake from happening. The shake from a failed stabilizer can be speed related when the steering is turned slightly or when the wheels hit a small bump, just right. With a little time most people figure out just how to induce the shakes. Once the shake starts it will not end until you virtually stop the vehicle. Start driving again and the condition will return it will return at the right speed or bump in the road.

Jeep CJ-7, Water Problems

WATER MIXING WITH OIL ISSUES ON JEEP


Question: I've got an '84 CJ-7, 258 straight six. There is quite a bit of water-oil mixture in the valve cover. I've notice just a tiny bit on the dip stick. But, when I drop the oil there is no water. Also, there is lots of water-oil accumulation in the air cleaner. And I notice the radiator is short on water about every two months. I get the feeling I have either a cracked block or a blown head gasket but the engine is actually running under temp during normal operation.?

A:There's no need to get physical. I don't believe that you're cooling loss is related to the watery-oil problem in the valve cover and air cleaner. It's not uncommon for a vehicle of that age to have small leaks that could account for the loss. The accumulation of water-oil in the air cleaner is a good indicator that the Positive Crankcase Ventilation (PCV) system is not functioning properly. Next, you're going to ask, "Where did the water come from that's in the engine?"

Have you seen condensation on a glass of water? Well, the same thing happens to engines. With temperature change, moisture will condense and collect inside an engine. But, that's only a small part of the picture. The greatest source of water in an engine is the combustion process, the burning of gasoline. How do you get water from gasoline? Gasoline is a hydrocarbon (HC). When gasoline is mixed with oxygen and heat, a thermal-chemical reaction occurs, it burns. Am I scaring you yet?

As the gasoline (HC) and oxygen (O2) burn, they break apart and re-join becoming water (H2O) and carbon dioxide (CO2). Of course there are other chemicals but these two are the main players. The remains of combustion (exhaust) H2O, CO2 and other chemicals are supposed to exit the tail pipe, but that doesn't happen. A portion of the combustion gases leak by the pistons in the engine, into the crankcase.

The job of the PCV system is to pull these gases H2O, CO2, and other chemicals out of the crankcase so as not to contaminate the engine oil. If the PCV system is not operating properly H2O will collect in the valve cover and be forced into the air cleaner assembly. Cold weather will make matters worse.

How to Check Vehicle Antifreeze/ Refrigerant:Coolant or Water?

Testing Antifreeze in vehicle

How do you check the antifreeze and water mixture in the radiator for corrosion?


I will mention the procedure we use at out garage.As per our auto garage experience,

The easiest and simplest manual procedure i will provide.

At shop we use test strips that report the concentration of anti-freeze and the acidity of the coolant. These test strips can be found in most automotive parts stores and are really easy to use. You just dip the test strips in the coolant and compare the color of the test strip to the chart on the bottle they come in. It is a quick and reliable test and lets you know if the acidity of the coolant is at a damaging level. If the coolant is too acidic, the system must be drained and refilled with a 50/50 mix of anti-freeze and water. You should test the acidity of your vehicle's cooling system every oil change.


 

Various warning lights are coming up on dashboard

A LOT OF ON DASH WARNING LIGHTS ON VEHICLE

How to troubleshoot vehicles warning light

Vehicle's service engine light was on for a week, I thought it was because I did not put the gas cap on properly. As per vehicles owners manual it should take about 3 cycles for the light to go out. After a week the light was still on, so I took it to the dealership, they did a diagnostic test and said the 02 sensor skipped. They reset the computer so that the engine light went out. A week later, the engine light is back on, afterwards the battery light came on and shortly after that the ABS indicator light came on. As I was driving home the radio went out and the lights inside the car started to dim. After shutting the car off, I tried to restart and it wouldn’t. The headlights did come on. I noticed as I put the security alarm on the car, it sounded weak. 
Any better idea of what may be wrong with this vehicle, so that I can trust, when I take it to the shop, I have some sort of idea what is going on with the vehicle.


Its a random issue,there are multiple possibilities to cause these problem

It’s very unlikely that the check engine light from the week before is related to the problem you’re having now. As per the problem  described I suggest to test charging system of the vehicle.It seems that the charging system on your vehicle has failed. The first indicator was the battery warning light. The job of the charging system is to provide electrical power for the vehicle’s needs and replenish the battery. The main job of the battery is to store electrical power for starting the engine. After the engine is running the charging system takes over. In the event of a charging system failure the vehicle’s electrical demands are supplied by the battery. On today’s vehicles it doesn’t take long for the battery to drain to the point that other computer systems take notice. When they see that the power supply to them is too low to operate correctly the other computers start complaining which would explain your ABS warning light. As the battery gets lower the radio will drop out, which is just about the time the engine computer will start thinking about throwing in the towel. At this point the battery has about enough power to light some lights but wouldn’t even think about cranking the engine over. The fix for your vehicle is likely a new alternator. Once you’re up and going the check engine light may come back on because of the O2 sensor problem, but that won’t kill the battery.

How to retrieve OBD error codes without scan tool?

IS IT POSSIBLE TO ACCESS OBD ERROR CODES MANUALLY

Been in the automotive trade for  years, I’m an ASE triple master tech, and love computerized technology. My problem is tapping into the OBDII computer for diagnostic codes, like it was done with EEC, CCC, etc. At this time I am running a small shop on my own, part time, and cannot warrant the cost of big time diagnostic equipment. Is there a way to jump terminals or something to get into the newer systems to access error codes?? 


At present the simple answer is NO.
But you cannot challenge inventions,tricks and R&D .The procedure an any time get created.
Now a days newer vehicle’s computer systems have a new generation of advanced On Board Diagnostics which is affectionately referred to in our industry as OBD II. The reason of the OBD II system was to create a common data port, with a common protocol, for accessing information, primarily emissions related. The key word is integrated. The days of using a jumper wire or pin to flash codes from a vehicle’s computer is quickly fading away. If you wish to communicate with today’s vehicle computers you need to determine the level of information you want access to. The more information you want the more money you have to pay. A low dollar tool, for checking codes, turning off the Check Engine Light and with a wee bit of the computer info, cost around $300 to $400. For the privilege of the above, viewing more and opening a door or two to the computer jumps the price tag up to $2000 to $3000. Annual software updates range from $600 to $2000 and does not cover every vehicle. Now if you want the high, the book store, encyclopedia factory of information and the ability open all doors in today’s vehicle computers you need the vehicle manufacturer’s scan tool and software. Yeah it costs more but wow does this tool make things happen, but it only works on that manufacturer’s vehicle.

Thanks.

1991 vehicle with recalls

My vehicle is under recall

If I own a ‘91 vehicle with recalls can I bring it to a shop/dealership for repairs... and are they for free? 



First you have to understand that recalls come in different flavors; voluntary and safety. A recall will commonly have a time and/or mileage limitation. If the recall is a safety recall the age or ownership of the vehicle is not a factor. To have the repairs performed at no cost requires that the work be done at the dealer. In the event you have had safety related repairs performed prior to the announcement of the safety recall, manufacturers have historically reimbursed the vehicle owner for those repairs if they present their receipt of the repairs.

Consumers can get up-to-the-minute information on safety recall campaigns, or information on the recall history of a particular make and model of the car or truck, by calling the National Highway Traffic Safety Administration Agency's toll-free Auto Safety Hotline at 1-888-DASH-2-DOT (1-888-327-4236), or by accessing NHTSA on the Internet at www.nhtsa.dot.gov.


Thanks.